Tag: p- block elements-ii

Questions Related to p- block elements-ii

Potassium nitrate decomposes above $336^oC$ to give

  1. $NO _2$

  2. $N _2$

  3. $O _2$

  4. $NO$


Correct Option: C
Explanation:

$2KNO _3\overset{\Delta}{\rightarrow}2KNO _2+O _2\uparrow$

Joseph Priestley discovered oxygen.

  1. True

  2. False


Correct Option: A
Explanation:

Priestley discovered oxygen gas in 1774. When he heated mercuric oxide, he found that a gas was released that could reignite a glowing splinter. This gas was oxygen.

During the experiment done by Antonie Lavoisier for discovery of oxygen, the level of mercury in the bell jar rose by:

  1. one-tenth

  2. one-third

  3. half

  4. one-fifth


Correct Option: D
Explanation:

The level of mercury in the bell jar rose by one-fifth during the experiment performed by Antonie Lavoisier.

What was the observation made by Joseph Priestley during the experiment done for discovery of oxygen?

  1. A coloured gas is collected in the jar

  2. A colourless gas is collected in the jar

  3. No gas is collected in the jar

  4. None of the above


Correct Option: B
Explanation:

During the experiment performed by Joseph Priestley, the observation was that a colourless gas is collected in the jar i.e oxygen.

The things or apparatus not used by Joseph Priestley was:

  1. sun rays

  2. mercuric oxide

  3. convex lens

  4. bell jar


Correct Option: D
Explanation:

Joseph Priestley did not use bell jar in his experiment.

During discovery of oxygen by Joseph Priestley, which compound was heated by focusing the sun rays on it?

  1. Silver oxide

  2. Mercuric oxide

  3. Zinc oxide

  4. Calcium oxide


Correct Option: B
Explanation:

During discovery of oxygen, mercuric oxide was heated by focusing the sun rays on it.

Who was the first scientist who named the oxygen gas?

  1. William Scheele

  2. Priestley

  3. Antoine Lavoisier

  4. None of the above


Correct Option: C
Explanation:

Antonie Lavoisier was the first scientist who named oxygen gas.

Oxygen has ______________ number of electrons in the outermost shell. 

  1. $6$

  2. $7$

  3. $8$

  4. $9$


Correct Option: A
Explanation:

Oxygen has $6$ electrons in the outermost shell. Its configuration is $2,6$.

If a species has $16$ protons, $18$ electrons and $16$ neutrons, find the species and its charge.

  1. $S^{1-}$

  2. $Si^{2-}$

  3. $p^{3-}$

  4. $S^{2-}$


Correct Option: D
Explanation:


$16p$ means $Z=16$

$18e$ means $2$ unit negative charge is present.

Hence, species is $S^{2-}$.

Which of the following is the correct order of melting points of group $16$ elements?

  1. $O<S<Se<Te<Po$

  2. $O<Se<S<Te<Po$

  3. $O < S < Se < Te > Po$

  4. $O < S < Se >Te < Po$


Correct Option: C