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

A man X goes to the top of a building by a vertical spiral staircase. Another man Y of the same mass goes to the top of the same building by a slanting ladder. Which of the two does more work against gravity and why?

What is a mixture? Give two example of mixtures.

Separate the following into physical and chemical changes:
Sublimation of a solid, Decomposition of water into hydrogen and oxygen by passing electric current, Formation of clouds, Making a fruit salad from raw fruits, Dissolving carbon dioxide in water.

What is meant by (i) homogeneous mixtures, and (ii) heterogeneous mixtures? Give two examples of homogeneous mixtures and two of heterogeneous mixtures.

What is the cause of buoyant force?

The atomic number of an element X is 16.
What will be the valency of X?

Explain why, the motion of a body which is moving with constant speed in a circular path is said to be accelerated.

The frequency of the sound emitted by the lioudspeaker is 1020Hz. Calculate the wavelength of the sound wave in air in cm where its velocity is 340m/s.

A man X goes to the top of a building by a vertical spiral staircase. Another man Y of the same mass goes to the top of the same building by a slanting ladder. Which of the two does more work against gravity and why?

State the location of electrons, protons and neutrons in an atom.