(i) Number and quality of chicks;
(ii) Dwarf broiler parent for commercial chick production;
(iii) Summer adaptation capacity/tolerance to high temperature;
(iv) Low maintenance requirements;
(v) Reduction in the size of the layer with ability to utilize more fibrous cheaper diets formulated using agricultural by-products.

(i) Exposure to air borne diseases can be prevented by providing living conditions that are not overcrowded.
(ii) Exposure to water borne microbes can be prevented by providing safe drinking water i.e., water treated to kill any microbial contamination.
(iii) The person suffering from an infectious disease should be kept in isolation
(iv) One should take balanced diet to make the immune system strong.This will also help in preventing infectious diseases.

When an object falls freely towards the ground, its potential energy decreases and kinetic energy increases. As the object touches the ground, all its potential energy gets converted into kinetic energy. As the object hits the hard ground, all its kinetic energy gets converted into heat energy and sound energy. It can also deform the ground depending upon the nature of the ground and the amount of kinetic energy possessed by the object.

Time ascent = Time of descent = 2/6 = 3 sec
(a) For upward motion of the ball, 
v = 0, t = 3s, g = -9.8 ms^-2
As, v = u + gt
0 = u - 9.8 x 3
or u = 9.8 x 3 = 29.
(b) The hight, s = ut + 1/2 gt²
= 29.4 x 3 - 1/9 x 9.8 x 3²
= 88.2 - 44.1 = 44.1 m.
(c) the position of the ball after 4 s is given by
s = ut + 1/2 gt²  
= 29.4 x 4 - 1/2 x 9.8 x 4² = 117.6 - 78.4 = 39.2 m 
The ball is at a height of 39.2 from the ground or 4.9 m from the top.

Unbalanced forces. If the resultant of the several forces acting on a body is not zero, the forces are said to be unbalanced forces. Unbalanced forces produce a change in the state of rest or uniform motion of a body.
Examples:
(i) In a tug-of-war, when one of the two teams pulls the rope with a larger force, it is able to pull the weaker team towards it. Here teh two forces are not balanced. Therefore, is results in the motion of the weaker team towards the larger force along the rope.
(ii) When we stop pedaling a bicycle, it begins to slow down the road has small cracks and bumps. The bicycle has to overcome these imperfections, which slow down it. Forces which slow down the moving objects in this way recalled forces of friction.
so we can say that objects continue to move, with the same velocity unless acted upon by unbalanced forces.

Aves	Mammalia
1. They have beak.	1. They do not have beak.
2. Their body is covered with feathers.	2. Their body is covered with hair. Feathers are absent.
3. Forelimbs are modified into wings for flight.	3. Forelimbs are not modified into wings as in birds. However, forelimbs may be modified for various purpose.
4. They lay eggs.	4. Most of the mammals produce live young ones.
5. They do not have mammary glands to produce milk for young ones.	5. They have mammary glands to produce milk for young ones.

Number of atoms in 23 g of sodium =6.022 x 10²³
Number of atoms in 11.5 g of sodium = \(\frac { 11.5 }{ 23 } \times 6.022\times { 10 }^{ 23 }\)
=3.011 x 10²³ atoms
Number of atoms in 40 g of calcium = 6.022 x 10²³
Number of atoms in 15 g of calcium = \(\frac { 6.022\times { 10 }^{ 23 }\times 15 }{ 40 } \)
=2.25 x 10²³ atoms.
Therefore, 11.5g of sodium has more number of atoms than in 15g of calcium

Step 1: Pass the mixture through a filter paper, water and oil will pass through, iron and sulphur will be left as a residue.
Step 2: The liquid separated is a mixture of water and oil. Take it in a separating funnel. Oil is generally lighter and makes the upper layer. The water, the lower layer can be poured out. Oil will remain in the funnel.
Step 3: Dry the solid residue. Pass a magnet over the mixture. Iron filings get stuck to the magnet whereas sulphur remains unaffected. Thus iron and sulphur get separated. Water and oil are compounds. Iron and sulphur are elements.

When two or more substance are mixed at random, it forms a mixture. In a mixture the constituent are not chemically combined at random and, it forms a mixture. In a mixture the constituent ate not chemically combined and can be separated into pure substances even by physical processes.Sea water is a mixture of dissolved salt and water substances even by physical processes. Sea water is a mixture of dissolved salts and water. On heating water evaporates and solid salt is left behind. The composition of a mixture can be varied and the properties of a mixture depend on its composition. For example, various types of stainless steel with distinct properties can be prepared by mixing steel with different amounts of chromium and nickel.

The maximum loss in weight of solid will be observed, when it is completely immersed in salt solution because salt solution exerts more upthrust than tap water due to its greater density.

Given, power, P = 2 W, time, t = 1min = 60 s
Total work, W = Pt
= 2 x 60s = 120J
\(\therefore\) 1.5 J work is done in 1 beat.
\(\therefore\) 120 J work will be done in \(\frac{1\times 120}{1.5}\) = 80 beats
Therefore,number of beatsper min = 80.

According to the formula, density = \(\cfrac { mass }{ volume } \)
If radius of the earth is R, then its volume =\(\cfrac { 4 }{ 3 } \pi { R }^{ 3 }\)  [\(\therefore\)shape of the earth is spherical]
Mass of the earth,M = \(\cfrac { { gR }^{ 2 } }{ G } \) \(\left[ \therefore \quad g=\cfrac { GM }{ { R }^{ 2 } } \right] \)(1/2)
\(\therefore\) Density=\({ \cfrac { gR^{ 2 } }{ G } }/{ \cfrac { 4 }{ 3 } \pi { R }^{ 3 }=\cfrac { 3g }{ 4\pi RG } }\)
Thus, the average density of the earth is\(\cfrac { 3g }{ 4\pi RG } \) 

Diffusion	Osmosis
It occurs in any medium.	It occurs in liquid medium only.
Diffusing molecules may be solid, liquid or gaseous solutes.	It involves movement of liquid molecules only.
semipermeable membrane is not required.	Semipermeable membrane is required.

Vermicompost is a kind of manure prepared by using earthworms to hasten the process of decomposition of plants and animals refuse.

0

(a) Iron
(b)This is because the velocity of sound is much greater than that of the fastest car.
(c) The velocity of light (3X\(10^{ 8 }\) \(ms^{ -1 }\)).So the flash of lightining is seen much before the thunder reaches us.

Here u = 0, m = 10 kg, h = 20 m, g = 10 ms^-2
As v² - u² =2gh v² - 0² = 2 x 10 x 20
v=\(\sqrt { 400 } \) = 20 m/s
K.E.= 1/2 mv² = 1/2 x 10(20)² = 2000J
The velocity does not depends on the mass of the rock because the acceleration due to gravity under which the rock falls does not depend on mass.

(a) The gravitation force between two objects depends on
(i) their masses and
(ii) the distance between them.
(b) \(F\ =\ \frac { GMm }{ R } \)

(a) A body is said to be at rest if it does not change its position with respect to its surroundings.
(b) A body is said to be in motion if it changes its position with respect to its surroundings.
(c) Motion of vehicles moving on a road can be easily and directly perceived.
(d) We perceive the motion of air indirectly by observing the movement of dust, leaves and branches of trees.

(a) Radial symmetry: When any plane passing through the central axis of the body divide the animal into two exact halves that are approximately mirror images it is called radial symmetry. For examples, sponges, coelenterates and adult Echinoderms (e.g., starfish).
(b) Bilateral symmetry: An animal is said to have bilateral symmetry if its body can be divided into two halves by only one vertical plane passing through centre. Examples: Arthropodes (housefly), Molluscs (snail, octopus), Man, etc.
Most bilateral animals have dorsal surface (the keeps upwards) and ventral surface (faces the ground).

A proton is the lightest positive particle. It is obtained when the gas inside the cathode rays tube is hydrogen.
Characteristics of Proton:
(i) A proton is one of the fundamental particles of the atom and is present in the nucleus of all atoms.
(ii) Charge: The charge on a proton is equal in magnitude but opposite in sign to that of an electron. Thus, it possesses a unit positive charge or + 1.6x10^-27kg which is about 1837 times of a proton is equal to that of a hydrogen atom, i.e. 1.672x^-27kg. Which is about 1897 times the mass of the electron.

Atomic mass of zinc = 65.37 g
65.37 g of zinc contains = 1 mole of zinc = 6.023 x 10²³ atoms of Zn
1 g of zinc will contain = \(\frac { 6.023\times { 10 }^{ 23 } }{ 65.37 } \)= 9.21 x 10²¹ atoms.
1 atom of zinc = \(\frac { 1 }{ 9.21\times { 10 }^{ 21 } } \)= 1.08 x 10^-22 g.

(a) An element is a substance that can be broken into smaller stable parts.
(b) Liquid bromine and nitrogen (gas) are non-metallic elements.
(c) Silicon is metalloid.
(d) Malleability and ductility
(e) Mercury is a metal that is liquid at room temperature.

Water is a compound because:
(i) The composition of hydrogen and oxygen in water taken from any source is the same.
(ii) The properties of water are different from that of its constituents, i.e., H₂ or O₂.

(i) First the battery converts chemical energy into electrical energy. Then the bulb converts this electrical energy into heat and light.
(ii) Here, m = 500 kg, v = 0 and
u = 36 kmh^-1  = \(\frac{36\times 1000}{3600}\) = 10 ms^-1
\(\therefore\) Work done = Change in kinetic energy
= \(\frac{1}{2}m(v^2-u^2)=\frac{1}{2}\times 500(0-10^2)\)
= \(\frac{1}{2}\times 500\times 100\) = - 25000 Js^-1
So, it is negative because work is done to stop the car.