Look at the periodic table given below and answer the following questions.

Groups	I	II	III	IV	V	VI	VII	VIII
Oxide: Hydride:	R2O RH	RO RH2	R2O3 RH2	RO2 RH4	R2O5 RH3	RO3 RH2	R2O7 RH	RO4
Periods ↓	A     B	A     B	A     B	A     B	A     B	A     B	A     B	Transition Series
1	H 1.008
2	Li 6.939	Be 9.012	B 10.81	C 12.011	N 14.007	O 15.999	F 18.998
3	Na 22.99	Mg 24.31	Al 29.98	Si 28.09	P 30.974	S 32.06	Cl 35.453

(I) This table was given by:

1. Newland
2. Döbereiner
3. Mendeleev
4. Moseley

(II) According to this periodic table, the formula of the oxide of nitrogen is:

1. N₂O₃
2. NO
3. N₂O₅
4. N₂O₇

(III) The defect(s) of this periodic table is/are:

P — Anomalous pairs

Q — Separation of chemically similar elements.

R — Grouping of chemically dissimilar elements.

1. Only P
2. Both Q and R
3. Both P and Q
4. P, Q and R

(I) Mendeleev

(II) N₂O₅

(III) P, Q and R

Reason —
(I) The above table was given by Mendeleev. It was published in German journal in 1872.

(II) Mendeleev used letter 'R' to represent the element of that particular group. Hence the oxide of nitrogen in the periodic table is R₂O₅. Here 'R' is nitrogen. Hence, oxide of nitrogen is N₂O₅.

(III) Mendeleev's periodic table had anomalous pair, which did not follow Mendeleev's principle. Major defects in Mendeleev's periodic table were grouping of chemically dissimilar elements and separation of chemically similar elements.