When a body falls freely

• its PE is converted into KE

• its KE is converted into PE

• its mechanical energy is converted into heat energy

• None of the above

2.

Heat energy of an object is

• the average energy of the molecules of the object

• the total energy of the molecules of the object

• the average velocity of the molecules of the object

• the average potential energy of the molecules of the object

Taking into account, three isotopes of hydrogen and three isotopes of oxygen occurring in nature, how many different kinds of water molecules can we expect on the Earth?

• Six

• Nine

• Twelve

• Eighteen

Which one of the following acids is present in Vitamin C?

• Citric acid

• Ascorbic acid

• Lactic acid

• Folic acid

Which of the following changes when a particle is moving with uniform velocity?

• Speed

• Acceleration

• Velocity

• Position

Rocket works on the principle of conservation of

• mass

• energy

• momentum

• None of these

Wisdom teeth normally grow during the age of

• 12-15 yr

• 17-30 yr

• 34-40 yr

• 40-45 yr

Life of RBC in human blood is

• 30 days

• 60 days

• 120 days

• 15 h

The momentum of a heavy object at rest will be

• zero

• small

• large

• None of these

The heating element in an electric iron is made of

• iron

• tungsten

• nichrome

• copper