Olympiad Test: Achievers Section-2 - Class 7 MCQ

In a uniform speed, the change in position of the body remains the same for a particular interval of time. The distance travelled in option (a), (c) and (d) is the same, in (c) it is zero. But the distance changes in option (b). Hence, the answer is (b). 

Time  = 15 minutes 
distance = 8 km

 = 8 × 4 km/hour
= 32 km/h

The upper fixed point in the Celsius scale is 100°C, which is the boiling point of water.

Gases  expand the most upon heating because of the large intermolecular distances and less intermolecular force. Carbon dioxide being a gas will expand the most. 

A medium (solid) is required for conduction to take place.

The speed of light decreases with an increase in the density of the medium.

Let the height of the flag pole be ‘h’ The length of the light pole = 25 m The constant ratio of length of object to its shadow = 2.5 (given)

The chemical energy stored in two cells is more than in one cell. The electrical energy used by one bulb is less than the energy used by two bulbs. So, the bulb in the circuit that has one bulb and two cells will glow the brightest. 

A heater is used to obtain heat energy. For light energy, a bulb or other sources are used.

Here, only a change of state from liquid and solid to gas is seen, and no new substances are formed 

The candle started melting, but since no new substance was formed, it is a physical change.

Calcium is more reactive than hydrogen.

Magnesium is more reactive than zinc.

When a wind flows very fast, a low pressure is produced temporarily which is filled by the rushing wind nearby.

Sea and land breezes are caused because of an uneven heating of the earth and through convection currents.

Though substances contract on cooling. water expand when cooled beyond 4°C. This is known as anomalous behaviour of water.

Human beings are warm blooded, which means that their body temperature has to be maintained around a particular temperature which is 37°C or 98° F. Water plays an important role in this.