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

Which of the following are compounds?

1. CO
2. No
3. NO
4. Co

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

A mixture of sand and iodine can be separated by:

The number of valence electrons determines:

The SI unit of volume is cubic metre (m³). The common unit of measuring volume in litre (L). Then, 1L = …… dm3, 1L = ………. mL and 1 mL = …….. cm3.

A solution of copper oxide was prepared by heating, igniting and precipitation. Which of the following method will give higher ratio of copper oxide:

In hydrogen peroxide (H₂O₂), the proportion of hydrogen and oxygen by mass is:

1. 1 : 8
2. 1 : 16
3. 8 : 1
4. 16 : 1

The mass number of two atoms X and Y is the same (40 each) but their atomic numbers are different (being 20 and 18 respectively). X and Y are examples of:

1. Chemically similar atoms.
2. Isotopes.
3. Solid and liquid metals.
4. Isobars.

In which of the following conditions, the distance between the molecules of hydrogen gas would increase?

1. Increasing pressure on hydrogen contained in a closed container.
2. Some hydrogen gas leaking out of the container.
3. Increasing the volume of the container of hydrogen gas.
4. Adding more hydrogen gas to the container without increasing the volume of the container.

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

Which of the following substance cannot be broken down by a chemical method?

The atomic number of an element is 11. Therefore the number of electrons in the M-shell of its atom is: