If aluminium strips are replaced by plastic strips, we cannot predict whether the object is charged or not.

There are two states of motion:
(i) State of rest
(ii) State of motion.

The property of metals to produce ringing sound is called sonority.

Wood has higher ignition temperature than kerosene oil.

If the person is a pisciculturist does the breeding, hatching and rearing of fishes.

Various constituents of petroleum and their uses:
(i) LPG: Fuel for home and industry.
(ii) Petrol: Motor fuel, aviation fuel, solvent for dry cleaning.
(iii) Kerosene: Fuel for stoves, lamps and for jet aircraft.
(iv) Diesel: Fuel for heavy motor vehicles and electric generators.
(v) Lubricating Oil: Lubrication
(vi) Paraffin wax: Ointments, candles, Vaseline etc.
(vii) Bitumen: Paints and road surfacing.

P is carbon monoxide, Q is haemoglobin R is oxygen and S is carboxyhaemoglobin.

If the seat cover of rickshaw is very smooth, then the friction between our body and the seat is very small. Therefore, when the brakes are applied, we tend to slip.

Hormone is the term used for secretions of endocrine glands responsible for changes taking place in the body.

(a) Virus
(b) Fungi
(c) Bacteria.

Water is an important and precious resource. Nowadays it is polluted with many harmful substances such as sewage, toxic chemicals, silt etc. which get mixed with water. Many industries discharge harmful chemicals into rivers and streams. To avoid these situations many compulsory rules must be obeyed as various physical and chemical processes in the sewage treatment plants must be done before discharging sewage into the water bodies. At our individual level we should consciously save water and do not waste it. Reuse and Recycle should be our Mantra.

Forces can be of two types:
(i) Contact forces.
(ii) Non-contact forces.
(i) Contact forces : The forces that come into play when two objects come in contact with each other.
(a) Muscular force: The force which is exerted due to action of muscles is known as the muscular force. e.g., running, bending, walking etc.
(b) Frictional Force: The force responsible for changing the state of motion of an object. Equal and opposite forces are being exerted on an object when its surface comes in contact with other surface. e.g., a car or scooter comes to rest.
(ii) Non-contact forces: The forces that can be exerted from a distance without establishing a contact are called the non-contact forces.
(a) Magnetic forces : Force exerted by a magnet on another magnet or magnetic substances like iron is called magnetic force. e.g., Car sticking to an electromagnet.
(b) Electrostatic force : Force exerted by a charged body on another charged body or uncharged body is called electrostatic force. e.g., If we rub a comb with hair and bring it near some small bits of paper it attracts the bits of paper towards itself. This is electrostatic force.
(c) Force of gravity : The earth pulls every object towards its centre. The force exerted by the earth is called the force of gravity.

Uses of Bacteria:
(i) They are used to increase soil fertility by fixing nitrogen.
(ii) Some bacteria are used to produce antibiotics.
(iii) Lactobacillus bacterium converts milk into curd.
(iv) Some bacteria help in many functions of our body.
Uses of Fungi:
(i) Yeasts are used to prepare alcohol and vinegar by fermentation.
(ii) Mushrooms are eaten as food.
(iii) Penicillin is an antibiotic formed by a fungus called Penicillium.
Uses of Algae:
(i) Algae are used to make jellies.
(ii) Chlorella is used to obtain proteins.
(iii) Silicafrom diatoms are used in toothpastes.

The property which determines the shrillness or pitch of a sound is the frequency. So, if the frequency of vibration is higher, then we can say that the sound has a higher pitch. If the frequency of vibration is lower, we say that the sound has a lower pitch.
e.g. the drum vibrates with a low frequency. Thus, it produces a low pitched sound. Besides this, a whistle has a high frequency produces a sound of higher pitch. A bird makes a high pitched sound while a lion makes a low pitched roar. However, the roar of a lion is very loud while the sound of bird is quite feeble.

(a) Chromoplasts are the coloured plastids (except green) that give fruit and flower their colour.
(b) Chloroplasts are known as 'kitchen of the cell
(c) No, all plastids are not coloured. Leucoplasts are the colourless plastids.
(d) No, we will not see plastids in an animal cell as it is devoid of plastids.
(e) Rohit is inquisitive, attentive and has love and care towards nature

(a) A is petroleum and B is natural gas.
(b) A is thick liquid while B is gas.
(c) C is called fractional distillation
(d) D is kerosene.