The rails expand during the heat of a summer day
It's a base because it increases the concentration of hydroxid ions
Answer:
Here's what I get
Explanation:
1. Nickel sulfate
base + acid ⟶ salt + water
NiSO₄ is a salt of the base Ni(OH)₂ and the acid sulfuric acid.
Hydroxides of transition metals are insoluble; most sulfates are soluble.

2. Carbonate + acid
Most carbonates are insoluble.
They react with acids to form carbonic acid (H₂CO₃), which decomposes into water and carbon dioxide.

The answer is D . I hope this help you :) .
ωєℓℓ тнє ρнσѕρнσяι¢ α¢ι∂ мσℓє¢υℓєѕ αттα¢н тσ тнє мσℓє¢υℓєѕ σf тнє мιℓк, αи∂ тнαт ιи¢яєαѕєѕ тнє ∂єиѕιту αи∂ тнєи ѕєρєяαтєѕ тнєм fяσм тнє яєѕт σf тнє ℓιqυι∂ ιи ιт. тнє яємαιи∂єя σf тнє ℓιqυι∂ѕ,иσω нανιиg ℓєѕѕ ∂єиѕιту тнαи тнє ρнσѕρнσяι¢ α¢ι∂ѕ & тнє мιℓк мσℓє¢υℓєѕ, ѕσ ιт ιт иσω fℓσαтѕ σи тσρ.
нσρє ι ¢συℓ∂ нєℓρ уσυ.