Question

the same amount of heat energy is added to equal masses of lead, iron, basalt, and water at room temperature. Assuming no phase change takes place, which substance will have the smallest change in temperature?

Answer 1

After equal masses absorb equal amounts of heat, the substance
with the greatest 'specific heat capacity' will have the smallest change
in temperature.

The specific heat capacities of those substances are ...

Water . . . . .  4,181       joules per kilogram-°C
Lead . . . . . . . . 125.6
Iron . . . . . . . . . 460.5
Basalt . . . . . . . . . 0.84

It looks like water is the easy winner.

THAT's why, in the days before electric blankets, hot-water bottles
were used to warm up a cold bed ... not hot-iron bottles or hot-basalt
bottles.  A pound of hot water brings much more heat to the sheets 
than a pound of any of those others.