A.) half - life of a radioactive substance is defined as the time during which concentration of the substance becomes half the initial value.
The answer is B NaCI solid
Answer:
I belive the answer is A but the image quality is hard to tell.
Explanation:
As pressure increases the higher the melting point of rock becomes making it harder to melt, thats why molten rocks brought to the surface melt because of the change in pressure.
Answer: 
Explanation:
Heat of reaction or enthalpy change is the energy released or absorbed during the course of the reaction.
It is calculated by subtracting the enthalpy of reactants from the enthalpy of products.

= enthalpy change = ?
= enthalpy of products
= enthalpy of reactants
For the given reaction :



Answer:
It is fairly obvious that zinc metal reacts with aqueous hydrochloric acid! The bubbles are hydrogen gas. ... In fact, electrons are being transferred from the zinc atoms to the hydrogen atoms (which ultimately make a molecule of diatomic hydrogen), changing the charges on both elements.
Explanation: