Main scale reading = 7 x 10 = 70 mm.(∴ 1 cm = 10 mm)
Vernier coincidence = 6
Least count = 0.1 mm.
Zero error = Nil
The diameter of the ball = MSR + (V.C x L.C) ± ZE
= 70 mm + (6 x 0.1)
= 70 mm + 0.6 = 70.6 mm
radius of the ball = 70.6/2 (∴ r = d/2)
35.3 mm

(i) An alternating current (AC) generator, consists of a rotating rectangular coil ABCD called armature placed between the two poles of a permanent magnet.
(ii) The two ends of this coil are connected to the two slip rings S₁ and S_2. The inner sides of these rings are insulated.
(iii) Two conducting stationary brushes B₁ and B₂ are kept separately on the rings S₁ and S₂ respectively. The two rings S₁ and S₂ are internally attached to an axle.
(iv) The axle may be mechanically rotated from outside to rotate the coil inside the magnetic field. Outer ends of the two brushes are connected to the external circuit

(v) When the coil is rotated, the magnetic flux linked with the coil changes. This change in magnetic flux will lead to generation of induced current.
(vi) The direction of the induced current, as given by Fleming's Right Hand Rule, is along ABCD in the coil and in the outer circuit it flows from B₂ to B₁.
(vii) During the second half of rotation, the direction of current is along DCBA in the coil and in the outer circuit it flows from B₁ to B₂
(viii) As the rotation of the coil continues, the induced current in the external circuit is changing its direction for every half a rotation of the coil

In a household electric circuit, different home appliances are connected in parallel to one another due to the following reasons:
(i) The appliances can be operated independently. If one appliance is switched off, others remain unaffected.
(ii) Each appliance gets the same constant voltage.
(iii) In parallel connection of electrical appliances, the overall resistance of the circuit is reduced due to which the current from the power supply is high.

Gay Lussac's law of combining volumes.
Gay Lussac's law:
Whenever gases react together, the volumes of the reacting gases as well as the products if they are gases bear a simple whole number ratio provided all the volumes are measured-under similar conditions of temperature and pressure.

Hydrogen combines with oxygen to form water.
2H₂ + 2O₂ \(\longrightarrow \) 2H₂O
(1 volume) + (2 volumes) \(\longrightarrow \) (2 volumes)
                 (1:2:2)
One volume of hydrogen react with two volumes of oxygen to form two volumes of water vapour.
The ratio by volume which gases, bears is 1.2:2 which is a simple number ratio.

\(\frac { 1 }{ f } =\frac { 1 }{ u } +\frac { 1 }{ v } \)
\(\frac { 1 }{ 20 } =\frac { 1 }{ -600 } +\frac { 1 }{ v } \)
\(\frac { 1 }{ v } =\frac { 1 }{ 20 } -\frac { 1 }{ -600 } \)
= \(\frac { 1 }{ 20 } +\frac { 1 }{ 600 } \)
\(\frac { 1 }{ v } =\frac { 30+1 }{ 600 } =\frac { 31 }{ 600 } \)
\(v=\frac { 600 }{ 31 } \)
= 19.35 cm
b) Size of the image
\(m=\frac { -v }{ u } \)
= \(-\frac { v }{ (-u) } =\frac { -600 }{ 31 } \times \frac { 1 }{ -600 } \)
m=\(\frac { 1 }{ 31 } \)
Breadth of image =\(\frac { 1 }{ 31 } \)\(\times\)200 cm= 6.45 cm
Height of image = \(\frac { 1 }{ 31 } \) \(\times\)160 cm= 5.16 cm

Given
Force = 200N
Area = 5m²
As we know P = \(\frac {F}{A}\)
= \(\frac {200}{5}\)
Pressure = 40 Pascal

Permanent teeth are of four types (Heterodont), according to their structure and function namely incisors, canines, premolars and molars.

Mass number of an element is the total number of protons and neutrons present in the nucleus. Mass number is denoted by A.
Mass number = Number of protons + Number of neutrons.

Minerals are very important to maintain the physiological process in our body. They are the constituents of teeth, bones, tissues, blood, muscles and nerve cells.

(i) Take pea seeds soaked in water overnight
(ii) Wait for the pea seeds to germinate
(iii) Once the seedling has grown put it in a box with an opening for light on one side.
(iv) After sometime, it is observed that the stem has bent and grown towards the light. This proves the phototropism movement of the stem.

(i) Speed = \(\frac { Distance }{ Time } \)= Distance = 1 km = 1000 m
Time =100 s
Speed = \(\frac { 1000 }{ 100 } \) =10 m/s
(ii) \(\frac { Displacement }{ time } \) = Velocity
Displacement = 1 km = 1000 m
Time = 100 s
Velocity = \(\frac { 1000 }{ 100 } \) = 10 m/s.

Reproductive characters of mammals differ from those of Aves by
1. The presence of mammary glands.
2. Testes lie outside the body cavity enclosed in scrotal sacs.
3. Alecithal eggs.
4. Fertilization is always internal.
5. They give birth to young ones and feed their youngones with milk.
6. Placenta is a characteristic feature of mammals.

A ray of light going towards the centre of curvature is reflected back along the same path. It is a rule for construction of image formed by spherical mirrors.

The data processing in a computer is collecting data and converting it into information according to our needs and requirements.

After the filteration of a solution the liquid that collected is called filtrate.
In the process of fractional distillation the clear liquid collected is called distillate.

The last electron in these elements is filled in p subshells and hence these elements are called p-block elements. These elements are in group 13 to 18 in the periodic table.

The region around a magnet within which its influence can be experienced is called magnetic field.

Nervous tissue

Blood and lymph

Adipose tissue

Tendons join skeletal muscles to bones in our body

Xylem is composed of
(a) Xylem tracheids
(b) Xylem fibres
(c) Xylem vessels
(d) Xylem parenchyma
Phloem is composed of
(a) Sieve elements
(b) Companion cells.
(c) Phloem fibres
(d) Phloem parenchyma

Sclerenchyma cells are grouped into (a) fibres and (b) sclereids.

(M) (n = 3) 2 x 3² = 18 electrons
(N) (n = 4) 2 x 4² = 32 electrons

When a ray of light passes from air into glass the angle of refraction is lesser than the angle of incidence.

When we put the ice cube in a glass of water it will float because density of ice cube is lesser than water. So it will float.
When we put the ice cube in a glass of alcohol it will sink because density of ice cube is greater than alcohol. So it will sink.
Density of water = 1 g cm^-3
Density of ice cube = 0.917 g cm^-3
Density of alcohol = 0.789 g cm^-3