We can align paragraphs in Word so the right sides are symmetrical. This is called right alignment.

When water attains the temperature of 100°C it starts changing its state from liquid to gaseous state. The temperature of water does not rise above 100°C. It is because the supplied heat energy only changes the state of the boiling water. This heat energy is stored in steam and it is called latent heat of vaporization of stear.

► A bird has streamlined body.
► Its bones are light and strong.
► They are hollow and have air spaces between them.
► The hind limbs of birds are modified as claws, which help them to walk and to perch.
► The breast bones are modified to hold massive flight muscles which help in moving wings up and down
►  Birds have special flight muscles and the forelimbs are modified as wings.
► The wings and tail have long feathers which help in flying.

Thermostat.
(i) A thermostat is a device which maintains the constant. temperature of a place or an object
(ii) The word thermostat is derived from two Greek words, thermo, meaning heat and 'static' meaning staying the same.
(iii) Thermostats are used in any device or system that gets heated or cools down to a pre-set temperature 
(iv) It turns an appliance on or off when a particular temperature is reached.
(v) Sometimes, a thermostat functions both as the sensor and the controller thermal of a system.
(vi) Examples for thermostats include building heater, central heater in a room, air conditioner water heater, as welt as kitchen equipments including oven and refrigerators.

No because Dinosaurs are extinct species. So, it is not possible to find Dinosaurs today.

(i) The bacteria present in our mouth decompose the food particles stuck in the gaps between our teeth thereby causing acid formation which leads to tooth decay. This causes dental caries.
(ii) To prevent dental caries we have to neutralize the acid. when we brush with toothpowder or tooth paste containing weak bases the acid gets neutralized.
(iii) Due to improper brushing of teeth heshna have caries in teeth.

(i) When a girl reaches puberty at the age of about 10, the sex hormones released into her blood cause some of the ova in her ovaries to become mature.
(ii) Usually one mature ovum is released from one of the ovaries into the oviduct once in every 28 days. This is called ovulation
(iii) Before ovulation the inner wall of uterus becomes thick and spongy, and full of tiny blood vessels. It prepares itself to receive the fertilized ovum.
(iv) If the ovum does not get fertilized then the thick and soft inner lining of uterus is no longer needed and hence it breaks. So the thick and soft inner lining of uterus along with the blood vessels and the dead ovum comes out of the vagina in the forrn of a bleeding called menstruation.
(v) Menstruation usually occurs 14 days after ovulation and usually lasts for about 3 to 5 days.
(vi) After menstruation is over, the inner lining of the uterus starts building up again so that it may become ready to receive the next ovum.
(vii) If the ovum does not get fertilized even now then menstruation takes place again. This cycle of menstruation is repeated again and again in women after every 28 days. The menstrual cycle is controlled by hormones.

\(\text { a) } \mathrm{C}+\mathrm{O}_{2} \rightarrow \mathrm{CO}_{2}\)
b) skeleton equation : \( \mathrm{P}+\mathrm{Cl}_{2} \rightarrow \mathrm{PCl}_{5} \)
Balanced equation : \( 4 \mathrm{P}+10 \mathrm{Cl}_{2} \rightarrow 4 \mathrm{PCl}_{5} \)
\(\text { c) } \mathrm{S}+\mathrm{O}_{2} \rightarrow \mathrm{SO}_{2}\)
c) skeleton equation : \(\mathrm{Mg}+\mathrm{HCl} \rightarrow \mathrm{MgCl}_{2}+\mathrm{H}_{2} \)
Balanced equation : \(\mathrm{Mg}+2 \mathrm{HCl} \rightarrow \mathrm{MgCl}_{2}+\mathrm{H}_{2} \)

Effects of Acid rain
(i) It irritates eyes and skin of human beings
(ii) It inhibits germination and growth of seedlings
(iii) It changes the fertility of the soil, destroys plants and aquatic life.
(iv) It causes corrosion of many buildings, bridges etc.
Preventive measures
(i) Minimising the usage of fossil fuels such as petrol, diesel etc.
(ii) Using CNG (Compressed Natural Gas)
(iii) Using non-conventional source of energy
(iv) Proper disposal of the industrial wastes.

Lightning:
i) Lightning is an example of discharge that takes place in clouds.
ii) Lightning is produced by discharges of electricity from cloud to cloud or from cloud to ground.
iii) During thunderstorm air is moving upward rapidly and it carries small ice crystals upward. At the same time, small water drops move downward.
iv) When they collide, ice crystals become positively charged and more upward and the water drops become negatively charged and move downward.
v) So the upper part of the cloud is positively charged and the lower part of the cloud is negatively charged.
vi) When they come into contact, electrons in the water drops are attracted by the positive charges in the ice crystals.
vii) Thus electricity is generated and lightning is seen.
viii) Sometimes, the lower part of the cloud which is negatively charged comes into contact with the positive charges accumulated near the mountains, trees and even people on the earth.
ix) This discharge produces a lot of heat and sparks that results in lightning.
x) Huge quantities of electricity are discharged in lightning flashes and temperatures of over 30,000°C or more can be reached.

Crop rotation is planting a series of different crops in the same field following a defined order.

1. Kayathar,
2. Aralvaimozhi,
3. Palladam,
4. Kudimangalam.

Kalpana Chawla, Sunitha Williams.

(i) Amplitude: Amplitude is the maximum displacement of a vibrating particle from its mean position. It is denoted by 'X. The unit of amplitude is metre (m).b.
(ii) Loudness is defined as the characteristic of a sound that enables us to distinguish a weak or feeble sound from a loud sound. The unit of loudness of sound is decibel (dB).

i) Each magnetic pieces having two poles i.e each piece act as bar magnet.
ii) Hence eight poles are there.