Tri-blade radiation symbol
(A) Naoh + Hno3 == Nano3 + h20.
and it is acid based reaction.
(B) H + Br == Hbr. it is synthesis reaction
and it should be hydrogen gas with bromine gas if that was question then
H2 + Br2 == 2Hbr
(c) 3Agno3 + Alcl3 == Al (No3)3 + 3Agcl
it is double displacement. and we right the polyatomic ion in bracket that’s why no3 is in bracket.
please let me know if you need something
Answer: 
Explanation:
General representation of an element is given as: 
where,
Z represents Atomic number
A represents Mass number
X represents the symbol of an element
Beta decay : In this process, a neutron gets converted into a proton and an electron releasing a beta-particle. The beta particle released carries a charge of -1 units.

The given reaction would be represented as:

Answer:
A gas with a rotten egg smell is evolved
Explanation:
When iron fillings and sulphur were heated in the vessel, the following chemical reaction took place;
Fe(s) + S(s) -----> FeS(s)
This is a direct combination reaction.
Subsequently, when dilute H2SO4 is added, the following reaction takes place;
FeS(s) + H2SO4(aq) ------> FeSO4(aq) + H2S(g)
He immediately observes the evolution of a gas with a rotten egg smell.
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