Calcium hydroxide, traditionally called slaked lime is one.
Potassium
chem
A base reract with acids.
Yes. Calcium is very reactive and tarnishes in minutes, if not seconds and if left out will corrode away. It will reacts vigorously with water and will quickly be consumed.
Bronsted-Lowry's BASES are a substance that either contains hydroxide ions OH- or reacts with water to form hydroxide ions.
Lithium reacts vigorously (but not violently) with water.
Potassium
Yes. Calcium reacts vigorously with water producing hydrogen and calcium hydroxide.
Li does NOT react slowly with water. It reacts vigorously to produce LiOH + H2 gas.
Group one elements react vigorously with water.They even react when exposed to air.For example lithium reacts violently with water.
Water
Exothermic
Al2Br6 reacts vigorously with water with evolution of HBr and formation of Al-OH-Br species.
Zn
any substance (colored or not) with a density less than 1 will float on water
chem
A base reract with acids.