Galvanisation

Difference in :
(i) Molecular mass = 14 a.m.u. 
(ii) Number of atoms of elements = CH₂

Ethyne, C₂H₂

Reaction of an acid with a metal:
When an acid reacts with a metal, it forms a salt.
Hydrogen which is in all the acids gets displaced and liberated as hydrogen gas.
Acids + Metals \(\rightarrow\) Salt + Hydrogen gas

As the wire is bent in the form of a closed circle, it will be have like two resistors of 5\(\Omega \) each, connected in parallel. Therefore, the equivalent resistance can be calculated as:
\(\frac { 1 }{ R_{ eq } } =\frac { 1 }{ { R }_{ 1 } } +\frac { 1 }{ { R }_{ 2 } } \)
\(\frac { 1 }{ R_{ eq } } =\frac { 1 }{ 5 } +\frac { 1 }{ 5 } \)=\(\frac { 1 }{ R_{ eq } } =\frac { 2 }{ 5 } \)
\(\frac { 1 }{ R_{ eq } } =\frac { 5 }{ 2 } =2.5\Omega \)
The effective resistance between the two points at the ends of an diameter of the circle is 2.5 \(\Omega \).

Nichrome should be used as a heating element in an electric iron because its melting point is higher than iron and silver.

(i) (-Cl) Halogen (Chloro)
(ii) -OH) Alcohol

a) The electronic configuration of chlorine with atomic number 17 is
K L M
2 8 7
b) Electron dot structure of chlorine molecule Cl2 is

Michael Faraday in 1831 discovered that mechanical motion can produce current.

Direction of induced current is given by Fleming's right hand rule according to this rule, stretch the thumb, fore-finger and the middle finger of the right hand such that they are mutually perpendicular.
If the fore-finger points in the direction of magnetic field the thumb shows the direction of motion and middle finger points in the direction of induced current.

It is an extracellular fluid used in transportation.

Pancreatic trypsin

It is a vector quantity as it has both magnitude and direction.

Heated iron acts as a catalyst in the synthesis of ammonia. It accelerates the rate of reaction and hence acts as a promoter .

Carbon and highly reactive metals such as sodium, calcium, aluminium are used as reducing agents to reduce metal into metal.

Quenching makes steel very hard and brittle.

Translocation

The heat energy obtained in the form of steam from under the earth's crust is called geothermal energy.

(a) Good conductor : Silver Ag and Copper Cu
(b) Poor conductor : Lead Pb and Mercury Hg

(a) Dwarfism if less hormone; Gigantism if secreted more.
(b) Diabetes
(c) Goitre
(d) Masculine characters will not develop properly in male.

The receptors present in our tongue which detect the taste are called gustatory receptors.

Thyroxine is the hormone secreted by the thyroid gland. This hormone regulates the metabolism of carbohydrates, fats and proteins. By regulating the metabolism it helps in optimum growth and development of the body.

Hind brain

Ampere (A)

Resistance is inversely proportional to the area of cross-section of the wire. Since, thìck wire has a large area of cross-section, its resistance will be less. Thus, current will flow more easily through the thick wire.

A catalyst changes the rate of reaction without taking part in the reaction itself.

3Fe(s) + 4H₂O(g) →→ Fe₃O₄(s)  + 4H₂(g)

(a) The chemical formula of X is MgO (magnesium oxide).The chemical formula of 'Y' is Mg₃N₂ (magnesium nitride).
(b) When 'X, magnesium oxide dissolves ip water, it gives magnesium hydroxide.
The chemical reaction involved in it, is as follows: •
MgO + H₂O\(\rightarrow\) Mg(OH)₂

Carboxylic acid reacts with alcohols to form ester. For example, when ethanoic acid is warmed with ethanol in presence of a few drops of concentrated sulphuric acid as catalyst, an ester (ethyl ethanoate, commonly called ethyl acetate) and water are formed.
\(\underset{Acetic\ or\ ethanoic\ acid}{CH_COOH}+\underset{Ethanol}{C_2H_5OH}\xrightarrow{Conc. H_2SO_4}\underset{Ethyl\ ethanoate}{CH_3COOC_2H_5}+\underset{Water}{H_2O)}\)
Ester are sweet -smelling substances. So they are widely used in making perfumes and flavoring agents. Further, the reaction between a carboxylic acid and an alcohol to form a sweet ester is used as a test for alcohols as well as carboxylic acids.

(a) The reaction involved in obtaining pure alumina from the mineral bauxite having impurities of iron oxide and silica is:
        (i) \(\underset { Aluminiumoxide\\ (frombauxiteore) }{ { AI }_{ 2 }{ O }_{ 3 }(s) } +\underset { Sodiumhydroxide\\ \quad (hot) }{ 2NaOH(aq) } \rightarrow \underset { Sodiumaluminate\\ \quad (Soluble) }{ { 2NaAIO }_{ 2 }(aq) } +\underset { Water }{ { H }_{ 2 }O(I) } \)
    The iron oxide and silica (sand) present in the bauxite ore do not dissolve in sodium hydroxide solution. Therefore, they are separated by filtration.
       (ii) \(\underset { Sodiumaluminate }{ { NaAIO }_{ 2 }(aq) } +\underset { Water }{ { 2H }_{ 2 }O(I) } \rightarrow \underset { Aluminiumhydroxide\\ \quad (Whiteppt) }{ { AI(OH) }_{ 3 }(s) } +\underset { Sodiumhydroxide }{ NaOH(aq) } \) 
       (iii) \(\underset { Aluminiumhydroxide }{ { 2AI(OH) }_{ 3 }(s) } \underrightarrow { heat } \underset { Aluminiumoxide\\ \quad (Pure) }{ { AI }_{ 2 }{ O }_{ 3 }(s) } +\underset { Steam }{ { 3H }_{ 2 }O(g) } \)
(b)

The salivary glands secrete saliva. The saliva contains water, salts, mucus and an enzyme ptyalin. The enzyme ptyalin, also glycogen and convert them into maltose. The mucus and water makes the food soft and slippery for the formation of bolus and also protects soft lining of alimentary canal. Thus the digestion of starch i.e., carbohydrate begins in the mouth. Since,the food remains in the mouth only for a short time and so, the digestion of food remains incomplete.
\(Starch(Carbohydrates)+Glycogen\overset { Ptyalin }{ \longrightarrow } Maltose\)
The partially digested food is further digested in the stomach. The food is broken down into smaller pieces and churned to form a semi-solid paste. The wall of the stomach contains three tubular glands. These glands secrete gastric juice. The gastric juice contains hydrochloric acid, mucus, pepsin, gastric lipase and rennin.
Hydrochloric acid:
It softens the food
It makes food acidic for the function of pepsin
It stops the action of salivary amylase
It kills germs and bacteria to disinfect the food
It converts inactive pepsinogen and prorennin into active pepsin and rennin.
\(InactivePepsinogen\overset { HCI }{ \longrightarrow } ActivePepsin\\ InactivePro-rennin\overset { HCI }{ \longrightarrow } Activerenin\)
Pepsin: It hydrolyses proteins into soluble proteoses and peptones only in presence of hydrochloric acid.
\(Protein\overset { Pepsin }{ \longrightarrow } Peptones+Proteoses\)
Rennin: It is active only in infants. The main function of rennin is that it converts soluble milk protein casein into insoluble protein called paracasein. Due to this, milk stays in stomach for longer duration.
\(\underset { (solublemilkprotein) }{ Casein } \overset { Rennin }{ \longrightarrow } \underset { (Insoluble) }{ Paracasein } \)
Mucus: The main function of mucus is to protect the inner lining of stomach from corroding action of hydrochloric acid as well as from pepsin enzyme.
Small Intestine: It is the seat of major digestion and absorption. Small intestine receives the secretion of two glands namely,
(i) Liver, (ii) Pancreas
Liver: It is the largest gland of the body. It is reddish brown in colour. It has soft pear - shaped sac called gall bladder. The gall bladder secretes bile juice. Bile is alkaline containing bile pigment. Thus, bile is stored in the gall bladder. It helps to emulsify or break the fats or lipids present in the food.
The bile performs the following functions:
(i) It breaks the larger globules of fat into small globules to make the enzyme to act and digest them.
(ii) It prevents putrefaction of food.
(iii) The bile creates a medium for the pancreatic juice to act on food by neutralizing the acidity in the food.
Pancreas: Pancreas secretes a digestive fluid called pancreatic juice. This juice contains digestive enzymes such as trypsin, nucleases, pancreatic lipase and pancreatic amylase. The enzyme trypsin digests the proteins, the enzyme pancreatic amylase breaks down the starch and the enzyme lipase breaks down the emulsified
facts. Pancreas produces two important hormones namely,
(i) Insulin, (ii) Glucagon
Insulin is essential for using glucose and storing it into glycogen. Glucagon is essential for conversion of glycogen into glucose. The alkaline medium is favourable
for the action of pancreatic enzymes.
\(Starch\xrightarrow [ ]{ Pancreaticamylase } Maltose\\ Fat\xrightarrow [ ]{ Lipase } Fattyacids+Glycerol\\ Proteins\xrightarrow [ ]{ Trypsin } Peptides\)
Secretion of intestinal juice by liver and pancreatic glands
The intestinal juice contains a number of enzymes which complete the digestion process. Here, the complex carbohydrates are converted into glucose, proteins are converted into amino acids and fats are converted into fatty acids and glycerol. All these end products i.e., amino acids, glucose, fatty acids and glycerol are small
and water soluble molecules. This complete digestion of food takes place by biological catalysts called enzymes. The intestinal juice includes - maltase, invertase, lactase etc.
\(Peptides\xrightarrow [ ]{ Trypsin } Aminoacids\\ Sucrose\xrightarrow [ ]{ Invertase } Glucose+Fructose\\ Maltose\xrightarrow [ ]{ Maltose } Glucose+Glucose\\ Lactose\xrightarrow [ ]{ lactose } Glucose+Galactose\)

A number of resistors are said to be connected in parallel if one end of each is connected to one point and the other end is connected to another point so that the potantial difference across each resistor is the same and is equal to the applied potential difference between the two points. If we connect a voltmeter first across R₁, then across R₂ ad lastly across R₃, it will show same voltage.

The endocrine and neural system both works together for the normal functioning of our body. The synthesis and release of certain hormones is regulated by the neural system. Also, the release of certain hormones influences the activity of nerves.
For example, hypothalamus receives neural signals from brain and releases hormones.
In case of deficiency of iodine, body produces less thyroxine hormone. Hypothalamus releases hormones to stimulate pituitary gland which further stimulates thyroid gland to secrete thyoxine.

(a) Concentrated sulphuric acid is called the king of chemicals as it is a very strong acid and is highly corrosive.

(b) The three chemical reactions that take place during the conversion of sulfur dioxide to sulphuric acid in the 'Contact Process' are given below.

Step I: Sulphur dioxide is mixed with air and passed over vanadiumpent (V) oxide catalyst heated to \(450^oC\) to form sulphur trioxide.

\(\underset{Sulphur\ dioxide}{2SO_{2(g)}}+\underset{Oxygen}{O_{2(g)}}\underset{\rightleftharpoons }{V_2O_5}\underset{Sulphur\ trioxide}{2SO_{3(g)}}+Heat\)

Step II : Sulphur trioxide is dissolved in concentrated sulphuric acid to form a thick fuming liquid called oleum.

\(\underset{Sulphuric\ acid}{H_2SO_4(l)}+\underset{Sulphur\ trioxide}{SO_{3(g)}}\begin{matrix} V_2O_5 \\ \rightleftharpoons \\ \end{matrix}\underset{Oleum}{H_2S_2O_{7(l)}}\)

Step III: Oleum is diluted with a calculated quantity of water to obtain sulphuric acid.

\(H_2S_2O_{7(l)}+\underset{Water}{H_2O_{(l)}}\rightarrow\underset{Sulphuric\ acid}{2H_2SO_{4(aq)}}\)

(c) If water is added to sulphuric acid then a large amount of heat is evolved.  This changes water to steam, which can splash the acid.  Hence, it is dangerous.

The reaction between an acid and a base that gives a salt and water is known as a neutralisation reaction.
Base + Acid ➝ Salt + Water
NaOH(aq) + HCI(aq) ➝ NaCl(aq) + H₂O(I)

N₂ + H₂ \(\rightarrow \)  NH₃ (Unbalanced equation).
(i) Examine the number of atoms of different elements present in the unbalanced equation.
(ii) In the above reaction, left hand N₂ and H₂ of both the sides are unbalanced.
(iii) To balance hydrogen, H₂ is multiplied by 3 on side. It makes 6H-atoms on the left hand side.
(iv) Now to balance hydrogen atoms on the right hand side, NH₃ should be multiplied by 2. It makes 6H-atoms on this side.
(v) Now to balance nitrogen atoms, they are counted separately for both the sides and we will find that, nitrogen atoms are 2 on both the sides.
(vi) Balanced chemical equation will be :
N₂ + H₂ \(\rightarrow \)  NH₃.

Water of crystallisation is a fixed number of water molecules present in one formula unit of a salt. One formula unit of copper sulphate contains five water molecules (SH₂O). The water molecules which form
part of the structure of a crystal are called water of crystallisation.
\(\underset{(Hydrated\ copper\ sulphate)\\(Blue)}{CuSO_4.5H_2O}\xrightarrow{Heat}\underset{(Anhydrous\ copper\ sulphate)\\(White)}{CuSO_4}+\underset{Water\\(Goes\ away)}{5H_2O}\)
Due to loss of water of crystallisation.
\(\underset{Anhydrous\ copper\ sulphate\\(White)}{CUSO_4}+\underset{Water}{5H_2O}\longrightarrow\underset{Hydrated\ sulphate\\(blue)}{CUSO_4.5H_2O}\)
By adding water

The major differences between an electric motor and generator are stated below:
Electric Motor:
1. It converts electrical energy into mechanical energy.
2. It needs electrical energy for its works.
3. They are used as water pumps, marble grinders etc.
Generator:
1. It converts mechanical energy into electrical energy
2. It needs mechanical energy for its working.
3. They are used as water pumps, marble grinders etc.
4. diesel generator, hydro-electric generator are the examples of it.

The different constituents of blood are plasma (the fluid part of the bloo(d) and blood corpuscles consisting of RBCs, WBCs, and platelets)
WBCs are known as the soldiers of the body because they fight against the pathogenes that invade our body, thus preventing the occurence of diseases.

(i) Oxygen enters the human body through the nasal passage and reaches the lungs.
(ii) Numerous alveoli are present in the lungs. These alveoli are surrounded by many blood capillaries. From the alveoli, 0₂ is taken up by the red blood cells present in the blood capillaries.
(iii) Similarly, the CO₂ from the various tissues is transported to the alveoli.
(iv) This CO₂ is then released through the nasal passage during exhalation. Alveoli are the sites of exchange of gases. Each lung contains 300- 350 million alveoli.
These alveoli increase the surface area for gaseous exchange, making the process of respiration more efficient.

(i) Magnesium reacts with water only on boiling.
(ii) Copper metal does not react even with steam.

(a) The solar cooker box is covered with a plane glass plate so as to prevent heat from escaping.
(b) Sun is said to be the ultimate and the original source for most of the energy present on the earth. When sun rays fall on oceans and other water bodies, the water present in the water bodies gets evaporated and rises up in the atmosphere. In the upper part of the atmosphere, this water vapour gets condensed and forms douds, which give rain on the high lands. Therefore, the rain water runs over the Sand surface towards the large water bodies. This running water over the land surfaces is called river. Therefore, the energy of running water actually originates from the solar energy. This is why solar energy of water flowing in a river is considered to be an indirect form of solar energy.
(c) The fission of nucleus is brought about by splitting the nucleus of heavy atoms, such as uranium or plutonium, with low-energy neutron bombardment. 

(a) A solar cell is a device which converts solar energy into electricity. It is a sandwich of a silicon-boron layer and a silicon-arsenic layer.
(b) Biogas is an ideal fuel for domestic use because it is a cheap and clean fuel, which does not leave behind any residue.
(c) A nuclear power plant is a device in which controlled chain reaction is used.

Voluntary actions are under the control of our will, it needs thinking. e.g. talking, walking. Involuntary actions are not under the control of our will, they are automatic. eg. salivation, heart beat.

(i) Regions included in central nervous system are the brain and the spinal cord. The brain and the spinal cord. The brain is further divided into three parts - forebrain, midbrain, and hindbrain.
(ii) Three of the functions of the brain are:
Forebrain controls intelligence, learning, memory, thinking, speech, etc.
Midbrain is associated with the sense of sight and hearing.
Hindbrain controls all involuntary actions such as breathing, peristalsis, etc.

(a) Short circuiting is the term used for defining the situation in which the neutral and live wires of an electric circuit come in direct contact. When too many electrical appliances are connected to a single socket, the appliances drawn much more current or power that the permissible limit from the main supply. This situation is termed as overloading.
(b) Resistivity of an alloy is much higher than its constituent metals Moreover, alloys do not oxidise as easily as the constituent metals at high temperature. Because of these reasons, coils of electric testers are made of an alloy rather than a pure meta.

(a)
  
(b) Electric current flowing through a bulb = \(\frac { Power\quad of\quad the\quad bulb }{ Voltage\quad across\quad the\quad bulb } \)
\(i.e.,\quad I=\frac { P }{ V } \)
Therefore, \({ I }_{ 60 }=\frac { 60W }{ 220V } =\frac { 3 }{ 11 } A\quad and\quad { I }_{ 40 }=\frac { 40W }{ 220V } =\frac { 2 }{ 11 } A\)
Therefore, total current flowing through the circuit  \(={ I }_{ 60 }+{ I }_{ 40 }=\frac { 3 }{ 11 } +\frac { 2 }{ 11 } =\frac { 5 }{ 11 } A=0.45A\)
(c) Total energy consumed = Power \(\times \) Time
      That is, E = P \(\times \) T
                      = (40W+60W)\(\times \)1h
                    = 100 Wh
                    = 0.1 kWh

(a) Element 'A' is non-metal because it belongs to Group VII therefore it has 7 electrons in its outermost shell. It needs one electron to acquire nearest inert gas configuration and form a monovalent -ve ion.
(b) Atom of element C has a larger size than that of element A because C belongs to the 3rd period therefore it has three shells whereas A belongs to the 2nd period thus it has two shells.
(c) Element B has a valency of 1 because it belongs to Group I and has one valence electron. To complete its outermost shell or to acquire nearest noble gas configuration it loses one electron and forms a monovalent +ve ion.

In a process called nuclear fission, the nucleus of a heavy atom (such as uranium, plutonium or thorium), when bombarded with low-energy neutrons, can be split into lighter nuclei with a release of tremendous amount of energy if the mass of the original nucleus is just a little more than the sum of the masses of the individual products.

The released energy can be used to produce steam and further generate electricity. The major hazard of nuclear power generation is the storage and disposal of spent or used fuels. Improper nuclear-waste storage and disposal result in environmental contamination. Further, there is a risk of accidental leakage of nuclear radiation. The high cost of installation of a nuclear power plant, high risk of environmental contamination and limited availability of uranium makes large-scale use of nuclear energy prohibitive. The only viable way to dispose off radioactive waste is to bury it deep underground. "The nuclear waste also should be guarded against any misuse.