Question : The surface tension of water on adding detergent to it:

Option 1: increases

Option 2: decreases

Option 3: no change

Option 4: becomes zero

Question : For a ray of light to suffer total internal reflection it has to pass from:

Option 1: glass to water

Option 2: water to glass

Option 3: air to water

Option 4: air to glass

Question : Fill in the blank with an appropriate option.
It is important to ensure that we all have good, clean water to drink that is not ______ by heavy metals or chemicals.

Option 1: knotted

Option 2: clarified

Option 3: purged

Option 4: contaminated

Question : Air is said to be saturated when -

Option 1: It contains the maximum content of water vapour.

Option 2: Its pressure is minimum.

Option 3: Its thickness is maximum.

Option 4: It blows over the barren land.

Question : A cuboidal water tank is 12 m long, 9 m wide and 7.5 m deep. How many litres of water can it hold?

Option 1: 840000

Option 2: 805000

Option 3: 780000

Option 4: 810000