Why is a control needed in a valid experiment?

Which expression represents the ΔH for a chemical reaction in terms of the potential energy, PE, of its products and reactants?

Difference between electrovalent and covalent bonding

What does an object need to contain in order for a magnet to be attracted

What is the mass of 2.13 moles of lithium arsenate

Hot, solid rock in the Earth's crust a. is cooler than surface lava because of the pressure of overlying rock. b. maintains uniform composition as it melts and becomes magma. c.

What is the concentration of Sr2 + in a saturated solution of SrSO4? SrSO4 has a Ksp of 3.2 x 10-7. 2.9 x 10-7 M 5.7 x 10-4 M 3.2 x 10-7 M 1.0 x 10-13 M

A binary compound created by reaction of nitrogen and an unknown element E contains 30.46% N and 69.54% E by mass. If the formula of the compound is N2E4, calculate the atomic mass of E.

How does the heat flow in a pot

In which medium would light have the longest wavelength?

Which type of organism can experience a mutation?