English Medium Class 9 - CBSE Question Bank Solutions for Science

Which separation technique will you apply for the separation of the following?

Tea leaves from tea.

Which separation technique will you apply for the separation of the following?

Wheat grains from husk.

Classify each of the following as a homogeneous or heterogeneous mixture.

Soda water, wood, air, soil, vinegar, filtered tea.

In a reaction, 5.3 g of sodium carbonate reacted with 6 g of acetic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium acetate. Show that these observations are in agreement with the law of conservation of mass.

Sodium carbonate + acetic acid → sodium acetate + carbon dioxide + water

Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas?

Which postulate of Dalton’s atomic theory is the result of the law of conservation of mass?

Why is it not possible to see an atom with naked eyes?

If bromine atom is available in the form of, say, two isotopes `""_35^79Br (49.7%)" and """_35^81Br (50.3%)`, calculate the average atomic mass of bromine atom.

The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes `""_8^16X" and """_8^18X` in the sample?

What do you mean by free fall?

What do you mean by acceleration due to gravity?

Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object?

What is the acceleration of free fall?

A ball is thrown vertically upwards with a velocity of 49 m/s. Calculate

1. the maximum height to which it rises.
2. the total time it takes to return to the surface of the earth.

A stone is released from the top of a tower of height 19.6 m. Calculate its final velocity just before touching the ground.

A stone is thrown vertically upward with an initial velocity of 40 m/s. Taking g = 10 m/s², find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone?

A stone is allowed to fall from the top of a tower 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m/s. Calculate when and where the two stones will meet.

A ball thrown up vertically returns to the thrower after 6 s. Find

1. the velocity with which it was thrown up,
2. the maximum height it reaches, and
3. its position after 4 s.

A certain household has consumed 250 units of energy during a month. How much energy is this in joules?

Suppose you and your friend are on the moon. Will you be able to hear any sound produced by your friend?