Water. — Science STD 8 — Question

Consider the statement given below and choose the correct option.
Assertion: A system can be converted from one state to another state.
Reason: It takes place when the temperature of the system is constant.

Assertion : Radiation is a process of transfer of heat in which a material medium is not necessary.
Reason : The heat from the sun reaches us through millions of miles of empty space by convection.

Assertion : When both the strips of electroscope is charged with similar charge, they repel each other and become wide open.
Reason : Like charges always repel each other.

Mark the correct one as:
Assertion: Malaria is caused by Protozoa.
Reason: The disease is transmitted by mosquito.

Assertion: Sound waves do not travel through vacuum.
Reason: The speed of sound Is too small when compared to speed of light.

Give a reason for the following.
Ice floats on water.

Assertion: To neutralise the excess acid formed in the stomach, milk of magnesia is taken.
Reason: Milk of magnesia contains a base called magnesium hydroxide.

Assertion : During inhalation, the diaphragm goes downward.
Reason : The volume of thoracic cavity decreases.

Assertion: With some samples of acids and bases, turmeric paper turns red.
Reason: Such samples are acidic in nature.

Consider the statement given below and choose the correct option.
Assertion: Iron filings are concentrated more at the magnetic poles.
Reason: The magnets are so sharp.