15
MCQ (Single Correct Answer)
Which of the following ions will cause hardness in water sample?
A
$\mathrm{Ca}^{2+}$
B
$\mathrm{Na}^{+}$
C
$\mathrm{Cl}^{-}$
D
$\mathrm{K}^{+}$
16
MCQ (Single Correct Answer)
Which of the following compounds is used for water softening?
A
$\mathrm{Ca}_3\left(\mathrm{PO}_4\right)_2$
B
$\mathrm{Na}_3 \mathrm{PO}_4$
C
$\mathrm{Na}_6 \mathrm{P}_6 \mathrm{O}_{18}$
D
$\mathrm{Na}_2 \mathrm{HPO}_4$
17
MCQ (Single Correct Answer)
Elements of which of the following group(s) of periodic table do not form hydrides?
A
Groups 7, 8, 9
B
Group 13
C
Groups $15,16,17$
D
Group 14
18
MCQ (Single Correct Answer)
Only one element of ........... forms hydride.
A
group 6
B
group 7
C
group 8
D
group 9
19
MCQ (Multiple Correct Answer)
Which of the following statements are not true for hydrogen?
A
It exists as diatomic molecule
B
It has one electron in the outermost shell
C
It can lose an electron to form a cation which can freely exist
D
It forms a large number of ionic compounds by losing an electron