Because they’re both made up of two substances that are not chemically combined
Reaction of Elemental Calcium with Water is as follow,
Ca + 2 H₂O → Ca(OH)₂ + H₂↑
When Sodium Metal is reacted with Water it produces NaOH and eliminates Hydrogen gas as shown in following equation,
2 Na + 2 H₂O → 2 NaOH + H₂↑
In both cases corresponding Hydroxides along with Hydrogen gas is produced.
Answer:
Substance 4
Explanation:
Density is defined as mass per unit volume. A substance floats in another when its density is less than that of the substance on which it floats.
If an object is immersed in a denser liquid, it will sink
Since the density of water is 1 g/cm^3, any substance whose density is less than that of water will float in it.
If we look at the table, substance 4 has a density of 0.5g/cm^3. Hence, substance 4 is expected to float in water.
