In X- H ----- Y, X, and Y both are electronegative elements. The correct statement among the following is:

1.	Electron density on X will increase and on H will decrease.
2.	In both electron density will increase.
3.	In both electron density will decrease.
4.	On X electron density will decrease and on H increases.

Nitrogen form $N_2$, but phosphorous  form $P_2$, it's at a time convert in $P_4$, reason is:

1. Triple bond present between phosphorous atoms. 
2. $\mathrm{p}\mathrm{\pi }-p\mathrm{\pi }$ bonding is weak in phosphorous.
3. $\mathrm{p}\mathrm{\pi }-p\mathrm{\pi }$ bonding is strong in phosphorous.
4. Multiple bonds easily form phosphorous.

Choose the incorrect statement among the following regarding noble gases:

In which one of the following arrangements the given sequence is not strictly according to the properties indicated against it?

Incorrect statement among the following is:

The correct statement among the following is:

General behavior of $O_3$ is: 

1. To give electrons
2. To Give $O_2$
3. Reaction with $H_2$
4. To accept electrons

A compound having two direct bonds between P and H atoms is:

1. $H_{3}P{O}_2$

2. $H_{3}P{O}_3$

3. $H_{3}P{O}_4$

4. $H_4{P}_2{O}_7$

Oxidation number of P in pyrophosphoric acid is:

1.  +5
2.  +2
3.  +3
4.  +4