Atoms and Molecules — Science STD 9 — Question

The material which is added to water during purification process at the water works so as to disinfect it is:

1. Potassium permanganate.
2. Betadine.
3. Chlorine.
4. Potash alum.

An atom is:

Value representing the number of protons in an element:

The theory of Democritus state that:

According to whose atomic model, electrons are embedded in a gel of positive charge:

Which of the following correctly represents 360g water?

1. 2 moles of H₂O.
2. 20 moles 0f water.
3. 6.022 × 10²³ molecules of water.
4. 1.2044 × 10²⁵ molecules of water.

1. (i)
2. (i) and (iv)
3. (ii) and (iii)
4. (ii) and (iv)

An ionic compound will be formed by the combination of one of the following pairs of elements. This pair of elements is:

1. Chlorine and calcium.
2. Calcium and sodium.
3. Sulphur and carbon.
4. Chlorine and chlorine.

One of the following does not undergo sublimation. This one is:

1. Iodine.
2. Sodium chloride.
3. Ammonium chloride.
4. Camphor.

For each of the following, use letters to indicate physical state of matter. ‘s’ for solid, ‘l’ for liquid ‘g’ for gaseous, 'p' for plasma, B.E.C. for Bose-Einstein Condensate.

S.No.	Specific Characteristic	Physical state
1.	Ionised gases
2.	Most ordered state
3.	Least ordered state
4.	Fixed volume, no shape
5.	Cooling gas at super low temperature

What is latent heat of vaporization: