If 450 mmol of calcium reacts with excess HCl how many moles of the gas are formed?

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture

If 1.8 l of water is added to 2.5l of a 7.0 molarity koh solution, what is the molarity of the new solution

The chemical equation below shows the reaction of sodium (na) and chlorine (cl) to form sodium chloride (nacl). 2na + cl2 → 2nacl in this equation, which of the following is a reactant? i. sodium ii. chlorine iii. sodium chloride