1. In which form does atom exists?
2. What is meant by saying that “the atomic mass of oxygen is 16”?
3. Which is the smallest atom and what is its size?
4. Write down the atomicity of the following elements:
Iron, Oxygen, Phosphorus, Chlorine, Ozone, Helium, Aluminium, Sulphur, Hydrogen and Argon.
5. Given reasons:
Atomicity of noble gases is one
Atomicity of metals is one.
6. The valencies of two elements A and B are given below:
A 1 +
B 2 +
(i) What is the formula of sulphate of A?
(ii) What is the formula of nitrate of B?
7. The formula of the chloride of a metal is MCl2 . What will be the formula of its sulphate?
8. Define gram atomic mass. What is the gram atomic mass of oxygen?
9. Define gram molecular mass. What is the gram molecular mass of oxygen?
10. Calculate the mass of the following:
(i) 0.5 mole of N2 gas (mass from mole of molecule)
(ii) 0.5 mole of N atoms (mass from mole of atom)
(iii) 3.011 × 1023 number of N atoms (mass from number)
(iv) 6.022 × 1023 number of N2 molecules (mass from number)
11. In Fig ABCDE is a pentagon. A line through B parallel to AC meets DC produced at F. Show that
(i) ar (ACB) = ar (ACF)
(ii) ar (AEDF) = ar (ABCDE)
12. The side AB of a parallelogram ABCD is produced to any point P. A line through A and parallel to CP meets CB produced at Q and then parallelogram PBQR is completed (see Fig. ). Show that ar (ABCD) = ar (PBQR).
13. 13. A villager Itwaari has a plot of land of the shape of a quadrilateral. The Gram Panchayat of the village decided to take over some portion of his plot from one of the corners to construct a Health Centre. Itwaari agrees to the above proposal with the condition that he should be given equal amount of land in lieu of his land adjoining his plot so as to form a triangular plot. Explain how this proposal will be implemented.