\left. \begin{array} { l l } { 1 \times 10 ^ { 23 } } & { ( 2 ) 1.5 \t

1.	\left. \begin{array} { l l } { 1 \times 10 ^ { 23 } } & { ( 2 ) 1.5 \times 10 ^ { 23 } } \\ { 2 \times 10 ^ { 23 } } & { ( 4 ) 6 \times 10 ^ { 23 } } \end{array} \right.
Answer» Molecular mass of ammonia= 14+3=17 In 1 molecule (nh3) there are 1+3=4 atoms 1 mole (17 g) has Avogadro number of molecules 17 g= 1 mole 4.25g=4.25/17=0.25 moles 1 mole = 4×6.022×10^23 atoms 0.25 or 1/4 mole =6.022×10^23 atoms.

\left. \begin{array} { l l } { 1 \times 10 ^ { 23 } } & { ( 2 ) 1.5 \times 10 ^ { 23 } } \\ { 2 \times 10 ^ { 23 } } & { ( 4 ) 6 \times 10 ^ { 23 } } \end{array} \right.

Answer»

Molecular mass of ammonia= 14+3=17

In 1 molecule (nh3) there are 1+3=4 atoms

1 mole (17 g) has Avogadro number of molecules

17 g= 1 mole

4.25g=4.25/17=0.25 moles

1 mole = 4×6.022×10^23 atoms

0.25 or 1/4 mole =6.022×10^23 atoms.