Answer:
2NaClO₄ (aq) + Ni(NO₃)₂ (aq) → 2NaNO₃ (aq) + Ni(ClO₄)₂ (aq)
No reaction
Explanation:
NaClO₄ → Sodium perchlorate
Ni(NO₃)₂ → Nickel (II) nitrate
All the salts from nitrate are soluble salts
All the salts from perchlorate are soluble salts except for the KClO₄
Answer: 1) only a salt and water
An acid and base reacts together to undergo neutralization to form salt and water.

where HCl is an acid and NaOH is a base to form salt (NaCl) and water
.
Answer: 2) The formula of the hydrogen ion is often written as
.
All acids dissociate in water to give
ions.
Answer: 3) Arrhenius acids are substances that ionizes to yield protons in aqueous solution.

Arrhenius bases are substance that ionizes to yield hydroxide ions in aqueous solution.

Answer: 4) A conjugate acid base pair transfers hydrogen ion.
Here
accepts a proton and thus act as a base and the corresponding
is its conjugate acid.
Answer: 5) Bronsted Lowry acid is a substance that donates protons. Bronsted Lowry base is a substance that accepts protons.
and 

is a acid which accepts proton and thus acts as base to form conjugate acid
.
1L ------------ 1 kg
? ------------- 3.8 kg
3.8 x 1 / 1
= 3.8 L
The mass of a substance per unit volume is the substance's density.
D = m/v.