Is Matter Around Us Pure ? — Science STD 9 — Question

An iron sphere of mass 10kg has the same diameter as an aluminium sphere of mass 3.5kg. Both the spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same:

1. Acceleration.
2. Momentum.
3. Potential energy.
4. Kinetic energy.

Choose the correct unit for the relative density among the following:

Speed is to velocity as:

The ozone layer of the atmosphere blocks:

1. Infrared radiations.
2. Sunlight.
3. UV radiations.
4. Both UV and indrared radiation.

Value representing the number of protons in an element:

On converting 25°C, 38°C and 66°C to Kelvin scale, the correct sequence of temperatures will be:

1. 298K, 311K and 339K
2. 298K, 300K and 338K
3. 273K, 278K and 543K
4. 298K, 310K and 338K

The velocities of sound waves in four media P. Q, R and S are 18,000km/h, 900km/h, 0km/h, and 1200km/h respectively. Which medium could be a liquid substance?

There are four elements P, Q, R and S having atomic numbers of 4, 18, 10 and 16 respectively. The element which can exhibit covalency as well as electrovalency will be:

1. P.
2. Q.
3. R.
4. S.

Jupiter has about 317 times more mass than Earth. What can you infer from this fact? 

When a body moves with a constant speed along a circle, then which of the following is correct :