A solution of potassium hydroxide (KOH) was titrated against a solution of hydrochloric acid. It took 35cm3 of the hydrochloric acid to completely neutralise the potassium hydroxide. Work out how many moles of acid there were in this volume if the concentration of the acid was 2mol/dm³.

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

Type the letter that represents the correct location for each particle type below.

Observation and experimentation have led many scientists to accept a theory about the origin of the universe. this theory is called the big bang theory. scientific evidence collected and observed by scientists around the world suggests that the universe is ever expanding from a hot and dense initial state. what makes this a scientific theory? (2 points)