Question

Consider the following statements
1)Na, Mg and Al form a Dobreiner's trend.
2)Noble gases were placed in group VIII A in periodic table.
3)EO2 is the formula of oxide of EKa silicon .
The incorrect statement(s) is /are
a)Only I
b)OnlyII
c)OnlyIII
d)(II) and (III) ​

Answer 1

Answer:

a)Only I

Explanation:

1)Na, Mg and Al form a Dobreiner's trend - False

2)Noble gases were placed in group VIII A in periodic table - True

3)EO2 is the formula of oxide of EKa silicon - True

Answer 2

Answer:

The answer is d) (II) and (III) ​

Explanation:

1. The arithmetic mean of the atomic masses of the first and third elements in a triad is approximately equal to the atomic mass of the second element in this triad, according to the law of triads.

• The atomic mass of Na=23 and the atomic mass of aluminum =27
• The arithmetic means =$\frac{23+27}{2}$ =25 which is not equal to the atomic mass of magnesium.
• Also, these elements do not show similar properties.

Hence the first statement is wrong.

2. The noble gases are found in Group VIII-A of the periodic table.

• Chemically, these elements don't react with other elements or compounds. So the statement is true.

3. The element Eka silicon is Germanium, which forms oxides and its formula is $GeO_2$ .

So the statement is true