(a) Pineal gland
(b) Pituitary gland
(c) Thyroid gland
(d) Thymus

The criteria for Mendeleev periodic table was the use of atomic masses. Mendeleev arranged the elements in increasing order of their atomic masses and according to their chemical properties.

(a) -CO (keto group)
(b) -COOH (carboxyl group)
(c) -CHO (aldehydic group)
(d) -OH (hydroxyl group)

(a)Xylem- Transports water and dissolved minerals in plants.
(b)Phloem-Transport prepared food in plants.
(c)Pulmonary vein-Transports oxygenated blood from lungs to left ventricles of heart.
(d)Pulmonary artery -Transports deoxygenated blood from body to right ventricles.

(a)\(\underset{Nitrogen}{N_2}+\underset{Hydrogen}{3H_2} \xrightarrow{}Catalyst /773K\underset{Ammonia}{2NH_3}\)
It is a combination reaction
(b)\(\underset{Sodium Hydroxide}{NaOH}+\underset{Acetic\ acid}{CH_3COOH}\rightarrow\underset{Sodium\ acetate}{CH_3COONa}+ \underset{Water}{H_2O}\)
Since, number of various atoms present in both side is equal, thus it is balanced equation. It is a double displacement reaction.
(c)\(\underset{Ethanol}{C_2H_5OH}+\underset{Ethanoic\ acid}{CH_3COOH}\xrightarrow{Warmed/Conc.H_2SO_4}\underset{Ethyl\ Acetate}{CH_3COOC_2H_5}+\underset{Water}{H_2O}\)
Since, the number of various atoms present in both side is equal, thus it is a balanced equation. It is a combination reaction
(d)\(\underset{Ethene}{C_2H_4}+\underset{Oxygen}{3O_2}\rightarrow\underset{Carbon\ dioxide}{2CO_2}+\underset{Water}{2H_2O}+Heat+Light\)
It is redox reaction.

The reaction between an acid and base to form salt and water is called neutralisation reaction.
Acid + Base \(\rightarrow\) Salt + Water
e.g. HNO₃(aq) + KOH(aq) \(\rightarrow\) KNO₃ (aq) + H₂O(l)
HCl(aq) + NaOH(aq) \(\rightarrow\) NaCl(aq) + H₂O(l)

(a) A\(\rightarrow \) Oviduct or Fallopian tube;
     B\(\rightarrow \) Ovary;
     C\(\rightarrow \) Uterus;
     D\(\rightarrow \) Cervix;
     E\(\rightarrow \) Vagina.
(b) (i) Ovaries;
     (ii) Fallopian tube;
    (iii) Lining of the uterus.
(c) (i) The lining of the uterus becomes
    (ii) The lining of the uterus slowly breaks and comes out through the vagina as blood and mucous, if no fertilisation occurs.

(a) Functions of the following parts of human eye:
(i) Comea: Objects enters the eye through cornea.
(ii) Iris: Iris controls the size of the pupil.
(iii) Crystalline lens: It focuses the image of the object on the retina.
(iv) Ciliary muscles: Ciliary muscles hold the eye lens and change the thickness of eye lens while focussing.
(b) (i) Objective of such campaigns. To make people aware of corneal blindness and make them realise their duties towards the society by taking pledge for eye donation.
(ii) (a) One pair of eyes can give eyesight to two corneal blind persons and make them see this beautiful world.
(b) Our eyes can live even after our death. People belonging to all age groups, even people with medical conditions like cataract, diabetes, hypertension can donate their eyes.
(iii) Values developed in persons who actively participate in such programmes:
(a) Concern for others and social welfare.
(b) Responsible behaviour and awareness.

(a) Environmental pollution is an undesirable change in the physical, chemical or biological characteristics of the natural environment, brought about by man's activities. This pollution may affect the soil, rivers, seas or the atmosphere. 

(c) Biodegradable pollutants are sewage and agricultural waste.

(i) It is because carbon has four valence electrons, it cannot gain or loss four electrons because high energy is needed. It can only share four electrons.
(ii) It is due to strong covalent bonds and compact structure of diamond.
(iii) It is due to high to presence of free electrons in graphite because each carbon is linked to three more carbon atoms.
(iv) It is due to high percentage of carbon, it burns with sooty or smoky flame.
(v) Kerosene oil is mixture of saturated hydrocarbons therefore does not decolourise bromine water.

Some of the methods employed by plants to get rid of excretory products are as follows 
(i) Gaseous wastes (i.e. carbon dioxide and oxygen) are removed through stomata in leaves and lenticels in stems into the atmosphere.
(ii) Plants get rid of excess water by transpiration.
(iii) Some waste products are stored as resins and gums.
(iv) Plants also excrete some waste substances into the soil around them.
(v) Waste products may be stored in leaves, bark or any other plant part, which fall off.

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.

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.

Nuclear energy has three advantages:
(a) It has very high efficiency, small amount of nuclear fuel can produce large amount of heat energy which can be controlled and used .
(b) It does not release any harmful gases like S02' CO2, N02 etc. in the air which may cause acid rain or green house effect.
(c) Once the reaction is initiated it can go on automatically for decades unless we want to stop it.

Properties of magnetic field lines:
The magnetic field lines have the following properties:
(i) They originate from North pole of a magnet and end at its South pole, by convention.
(ii) These lines are closed and continuous curves.
(iii) They are crowded near the poles, where the magnetic field is strong and separated far from the poles, where the magnetic field is weak.
(iv) Field lines never intersect with each other. If they do, that would mean that there are two directions of the magnetic field at the point of intersection, which is impossible.

(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.

Plastic bags are non-biodegradable which can not be broken down into non-poisonous substances in nature.
Plastic bags are the main cause of sewer blockages as plastic bags are not decomposed by micro-organisms.
Plastic bags if eaten by stray animals can block their alimentary canal.
Two alternatives:
(1) We should take our own jute or cloth bags while going for purchasing articles from the market.
(2) Disposable paper cups should be used for serving tea in trains instead of plastic cups.
(3) Shopkeepers can use paper bags instead of plastic bags.