What form of matter is made of only one type of atom

Earth's atmosphere is composed mostly of nitrogen and oxygen. In order to float, a ballon has to be filled with something that is lighter than air.

What part of the graph would indicate a change is taking place

If a gas in a closed container is pressurized from 15.0 atmospheres to 16.0 atmospheres and its original temperature was 25.0 °C, what would the final temperature of the gas be?

What is the mass of water that results from combining 2.0g of hydrogen with 16.0g of oxygen?

What is the mass, in grams, of solute in 255mL of a 0.0525M solution of KMnO4 (MM = 158.04g/mol) ?

Identify the element that chlorine forms a covalent bond with

A child pulls a sled up a snow-covered hill. The child does 405 J of work on the sled. If the child walks 15 m up the hill, how large of a force must the child exert?

A piece of glass with a mass of 32.50 g specific heat of 0.840 J/g*°C and an initial temperature of 115 °C was dropped into a calorimeter containing 57 g of water (specific heat 4.184 J/g*°C).

Which of the following is the most likely description of the product or products of a double-displacement reaction? A) one new compound B) two new compounds C) oxygen and energy D) one new compound and an element

A balloon is filled with 12L of air at a pressure of 2 atm. What is the volume of ballon if the pressure is changed to 3 atm?