An element 'M' has 50% of the electrons filled in the 3rd shell as in the 2nd shell. The atomic number of 'M' is:

1. 10
2. 12
3. 14
4. 18

Mild non-corrosive basic salt is

1. Ca(OH)₂
2. NaCl
3. NaOH
4. NaHCO₃

On adding dilute sulphuric acid to a test tube containing a metal 'X', a colourless gas is produced when a burning match stick is brought near it. Which of the following correctly represents metal 'X'?

1. Sodium
2. Sulphur
3. Copper
4. Silver

An element with atomic number …………… will form a basic oxide.

1. 7 (2,5)
2. 17 (2,8,7)
3. 14 (2,8,4)
4. 11 (2,8,1)