It happen because when we react quick lime with water it releases heat energy and due to this it produces bubbles in water.
Product is
CaO + H₂O → Ca(OH)₂ + heat

Oxidation

(i) Aldehyde : \(\underset{\\\\ \ -\mathrm{C}-\mathrm{H}}{\overset{\mathrm{O}}{||}}\)
(ii) Alcohol: -OH

Functional group: Ketone, name of the compound: Propanone.

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

Hydrogen gas is formed. Bring a burning matchstick near to it, H₂ will burn explosively with 'pop' sound.

Gallium.

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

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

(i) Tthe electronic configuration (2, 8, 2) of the element 'M' suggests that it belongs to group 2 and period 3 of the Modern Periodic Table and its valency is 2.
(ii) The chemical formulae of the compounds formed are:
(a) M(NO₃)₂
(b) MSO₄
(c) M₃(PO₄)₂
(iii) 'M' will form ionic compounds by losing two valence electrons to achieve a noble gas configuration that is a stable octet in the valence shell.

Electric fuse is used for protecting the circuits due to short circuiting or overloading of the circuits.

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

It is an extracellular fluid used in transportation.

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

Cinnabar, Hgs

Enzymes are bio-catalyst which help in faster biochemical processes.

Respiration involves the breaking down of digested food using oxygen.As respiration produces a lot of energy in the form of ATP, this process is exothermic in nature.

The strength of magnetic field varies directly as the magnitude of the electric current. So, in case of an increase in current the magnetic field would increase.

Nuclear fusion is a nuclear reaction in which two light nuclei of a heavy atom combine to form a nuclear of a heavier atom.
The conditions required for the occurrence of a fusion are:
(a) High temperature
(b) Hogh pressure

The receptors present in our eyes are called photoreceptors, as they are light sensitive.

Brain and spinal cord.

Neurons are the functional units of the nervous system. They carry the information from the brain and the spinal cord to the different parts of the body and form the different parts of the body to the brain or the spinal cord.

A measuring instrument used to measure potential difference between two points in an electric circuit.

Calcium oxide (CaO), commonly known as quicklime 

A solution of ammonia in water results in the formation of ammonium hydroxide (NH₄OH).  Ammonium hydroxide is basic in nature and turns red litmus blue.

The differences between autotrophic and heterotrophic nutrition are as follows

The chemical formula of baking powder is sodium hydrogen carbonate \((NaHCO_3).\) while, that of washing soda is sodium carbonate carbonate on heating gives \(CO_2\) gas which will turn lime water milky whereas no such gas is obtained from sodium carbonate.

\(2NaHCO_3\xrightarrow {Heat}Na_2CO_3+H_2O+CO_2\)
\(NA_2CO_3.10H_2O\xrightarrow {Heat}Na_2CO_3+10H_2O\)

(i) Change in colour: Reaction between lead nitrate solution and potassium iodide solution.
Pb(NO₃)₂(aq) + 2KI \(\longrightarrow \) PbI₂(s) + 2KNO₃(aq)
In this reaction, colour changes from colourless to yellow.
(ii) Change in temperature: Action of dilute sulphuric acid on zinc.
Zn(s) + H₂SO₄(aq) \(\longrightarrow \) ZnSO₄(aq) + H₂
In this reaction, heat is evolved
(iii) Formation of precipitate : Action of barium chloride on sodium sulphate.
BaCl₂(aq)+ Na₂SO₄(aq) \(\longrightarrow \) BaSO₄(s) + 2NaCl(aq)

(a) (i) Physical state of reactants and products.
(ii) Conditions such as temperature, pressure, heat etc.
(iii) Catalyst involved.
(iv) Change in state. 
(b) Total mass of the elements present in the products in a chemical reaction has to be equal to the total mass of elements present in the reactants or Mass can neither be created nor. destroyed in a chemical reaction.

Three properties of sodium are:
(i) Sodium is so soft that it can be cut with a knife.
(ii) It has low density.
(iii) It has low melting point.

(i) Solution Y is a stronger acid.
(ii) Strong acid: An acid which dissociates completely in water and produces a large amount of hydrogen ions. e.g., HCI
Weak acid: An acid which dissociates partially in water and produces a small amount of hydrogen ions. CH₃COOH.

The transport of soluble products of photosynthesis is known as translocation. Translocation in plants occurs by means of the vascular tissue known as phloem. Translocation is necessary because without it, the food prepared by the leaves cannot reach other parts of the plant.
(i)In plants, the synthesis of sugars takes place in the leaves by the process of photosynthesis.
(ii)Hormones are synthesised away from their targrt site.

(i)The glottis is gaurded by epiglottis because it prevents the entry of food in wind pipe. If the food enters wind pipe, then it chokes it, leading to the death of the person.
(ii)The lung alveoli are covered with blood vessels because the oxygen that we inhale dissolves in the blood, present in these blood capillaries only, as it reaches the lungs.
(iii)The wall of trachea is supported by cartilage rings because these rings prevent the air passage from collapsing.

The name of the compound is cupric chloride which gives blue-green colour to the solution.
\(CuO+2HCI\rightarrow { CuCI }_{ 2 }+{ H }_{ 2 }O\)

A series of similarly constituted compounds in which the members present have the same functional group and similar chemical properties and any two successive members in a particular series differ in their molecular formula by ( - CH₂) unit, is called a homologous series.
e.g. alkane series C_nH_2n+2

(a) The solar cells are costly and hence the energy available from them expensive.
(b) 15 km/h is the minimum wind velocity required to obtain useful energy with a windmill.
(c) Nuclear fission is the process in which a radioactive atom splits up into smaller nuclei when struck with low energy neutrons.

(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.

(ii) When the key is closed, total voltage applied across the circuit will be = 2 ✕ 5V = 10 V
     Total resistance (R) applied across the circuit in Ohms = 5+10+15= \(30\Omega \) 
     By Ohm's Law,
     Current (I) = \(\frac { V }{ R } \)
       \(I=\frac { 10 }{ 30 } =0.33A\)

(a) Resistance is defined as the property of a conductor due to which it opposes the flow of current through it. The S.I. unit of resistance is Ohm \(\left( \Omega \right) \).
(b) (i) The resistance (R) of a conductor is related to its length (l) and area of cross section (A) as
          \(R=\frac { p\times l }{ A } \)  Where \(\rho \) is the resistivity of the conducting material.
Let R₁= Resistance of the original wire
      R₂= Resistance of the wire when its length is doubled
I₁= Length of original wire
l₂= Length of original wire when doubled
A₁= Area of the original wire
A₂= Area when it is halved 
Therefore,
 \({ R }_{ 1 }=\frac { P\times { l }_{ 1 } }{ { A }_{ 1 } } \quad \quad ---\quad (1)\\ { R }_{ 2 }=\frac { P\times { l }_{ 2 } }{ { A }_{ 2 } } \quad \quad ---\quad (2)\)
Dividing equation (1) and (2) by equation (1), we obtain
\(\frac { { R }_{ 1 } }{ { R }_{ 2 } } =\frac { { l }_{ 1 } }{ { l }_{ 2 } } \times \frac { { A }_{ 1 } }{ { A }_{ 2 } } \quad ---\quad (3)\)
It is given that:
\({ l }_{ 1 }=2l_{ 1 }\quad and\quad { A }_{ 2 }=\frac { 1 }{ 2 } { A }_{ 1 }\\ \)
Putting these values in equation (3), we obtain
R₂=4R₁
Hence, the resistance of the wire will be 4 times of the original value.
(ii) The resistivity will not change on stretching the wire. Resistivity is the property of the conducting material. It does not depend on the dimension of the wire. As materials of both the wires are the same, the resistivity will not change.

(i) The nature of the solution is acidic. It is a mixture of conc. HNO₃, and conc. HCI in the ratio of 1 : 3. It can dissolve gold as it is an oxidising agent.
(ii) Pure gold is 24 carat gold which is very soft.

Importance of Fuse: The electric fuse is an important device in household wiring and also in many electrical appliances. By melting, the fuse wire breaks the circuit and thus helps in saving the wiring or the appliance from damage. A fuse wire works because of its lower melting point which is possible because of its respective rating. If a fuse with larger rating is used with an appliance, the fuse wire shall not melt and hence would fail to serve the required purpose. Due to this, a fuse with defined rating should not be replaced by one with a larger rating.

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.

(a) The element A which is a yellow solid at room temperature and shows catenation and allotropy is sulphur (S).
(b) The atomic number of sulphur is 16. Therefore, its electronic configuration is 2, 8, 6.
(c) \(\underset { Ferroussulphate }{ { 2FeSO }_{ 4 } } \underrightarrow { Heat } \underset { Ferricoxide }{ { Fe }_{ 2 }{ O }_{ 3 } } +\underset { Sulphurdioxide }{ { SO }_{ 2 } } +\underset { Sulphurtrioxide }{ { SO }_{ 3 } } \)
    Both SO₂ and SO₃ are major air pollutions.
(d) Since sulphur is a non-metal, therefore both S02 and S03 are acidic oxide since they dissolve in water to form the corresponding acids.
        \(\underset { Sulphurdioxide }{ { SO }_{ 2 } } +\underset { Water }{ { H }_{ 2 }O } \rightarrow \underset { Sulphurousacid }{ { H }_{ 2 }{ SO }_{ 3 } } \\ \underset { Ferroustrioxide }{ { SO }_{ 3 } } +\underset { Water }{ { H }_{ 2 }O } \rightarrow \underset { Sulphuricacid }{ { H }_{ 2 }{ SO }_{ 4 } } \)
(e) Since sulphur contains six valence electrons, therefore it lies in group 6 + 10 = 16.Further, since atomic number of sulphur (S) is 16. It lies in the 3rd period.

i) All fossil are the remains of the prehistoric plants and animals. Th energy of the fossil fuels is in fact that solar energy which was trapped by natural processes a long time ago.
ii) Solar energy also appears in the form of energy of water flowing in rivers as is obvious from the water cycle in nature. It is this energy which generates in hydroelectric power plants.
iii) Biomass energy is also the solar energy absorbed by the plans which convert it into chemical energy through photosynthesis.
iv) Human and animals use bioenergy to carry out their life activities.
v) Solar energy is one of the main factors responsible for the movement of air in the atmosphere leading to wind energy.
vi) Solar energy is used directly in solar.