Dissolution of sodium hydroxide in water is exothermic or endothermic in nature?

 Dissolution of ammonium chloride in water is exothermic or endothermic in nature?

Identify the reducing agent in the following reactions.

 $4{\mathrm{NH}}_3+5{\mathrm{O}}_2 \underset{ }{\to } 4\mathrm{NO}+6{\mathrm{H}}_2\mathrm{O}$

Identify the reducing agent in the following reactions.

 ${\mathrm{H}}_2\mathrm{O}+{\mathrm{F}}_2 \underset{ }{\to } \mathrm{HF}+\mathrm{HOF}$

Identify the reducing agent in the following reactions.

 ${\mathrm{Fe}}_2{\mathrm{O}}_3+3\mathrm{CO} \underset{ }{\to } 2\mathrm{Fe}+3{\mathrm{CO}}_2$

Identify the reducing agent in the following reactions.

 $2{\mathrm{H}}_2+{\mathrm{O}}_2 \underset{ }{\to } 2{\mathrm{H}}_2\mathrm{O}$

Identify the oxidising agent (oxidant) in the following reactions.

 ${\mathrm{Pb}}_3{\mathrm{O}}_4+8\mathrm{HCl} \underset{ }{\to } 3{\mathrm{PbCl}}_2+{\mathrm{Cl}}_2+4{\mathrm{H}}_2\mathrm{O}$

Identify the oxidising agent (oxidant) in the following reactions.

 $2\mathrm{Mg}+{\mathrm{O}}_2 \underset{ }{\to } 2\mathrm{MgO}$

Identify the oxidising agent (oxidant) in the following reactions. 

${\mathrm{CuSO}}_4+\mathrm{Zn}\underset{ }{\to } \mathrm{Cu}+{\mathrm{ZnSO}}_4$