Structure of the Atom — Science STD 9 — Question

Mass of one atom of oxygen is formul:

Match the Column I with Column II.

S.No	Column I		Column II
a	9.033 × 1024 atoms	i	46g of He
b	2 moles of Na	ii	15 moles
c	11.2 L of O2, at STP	iii	3.011 × 1023 molecules
d	22g of CO2	iv	16g

The purpose of separating the components of a mixture is:

The latent heat of vaporization of water is:

1. 22.5 × 10⁶J/ kg
2. 3.34 × 10⁶J/ kg
3. 22.5 × 10⁴J/ kg
4. 3.34 × 10⁵J/ kg

Which among the following statements is true:

Molecular compounds are usually formed by the combination between:

When a gas jar full of air is placed upside down on a gas jar full of bromine vapours, the red-brown vapours of bromine from the lower jar go upward into the jar containing air. In this experiment:

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

Which of the following configuration is most likely to form an anion:

The mass number of a neutral atom is 31 electrons. What is the atomic number of this atom?