Can y'all tell me what's an atom and a mole

Why are the atomic masses for most elements not whole numbers?

A closed 5.00 L container is filled with a mixture of 4.00 moles of hydrogen gas, 8.00 moles of oxygen, 12.0 moles of helium, and 6.00 moles of nitrogen. What is the pressure due to the oxygen in this container at a temperature of 25 °C?

A solution has a [OH-] of 1 x 10-9. What is the pOH of this solution? a) 5 b) 7 c) 9 d) 12

Ip a gas has a temperature of 310 k and a pressure of 100 kpa. part a find the volume occupied by 1.20 mol of this gas, assuming it is ideal.

A liquid that occupies a volume of 2.68L has a mass of 2.40 kg. What is the density of the liquid in kg/L?

How many moles of carbon do you have in 100 quadrillion carbon atoms? report answer to 2 sig figs

A small 15 kilogram canoe is floating downriver at a speed of 4 m/s. What is the canoe's kinetic energy?

Liquid water is heated until it boils and becomes water gas. Which statement is true about the water?

You are conducting an experiment on plant growth. You take a plant fresh from the soil that weighs 5 kilograms (kg). Then you dry the plant overnight and determine the dry weight to be 1 kg.

What is the ratio of Fe+3 ions to O2 - ions in a neutral compound? a. 1:2 b. 2:1 c. 2:3 d. 3:2