When a solid melts

a. the temperature of the substance increases.

b. the temperature of the substance decreases.

c. heat energy leaves the substance.

d. heat energy enters the substance.?

What happens when a catalyst is added to a chemical reaction that is already in progress? the reaction reverses the reaction stops the rate of the chemical reaction decreases the reaction with the lower activation energy occurs

What forces keep balanced rock balanced on it'so tiny pedestal.

SeH2 molecule - - How many lone-pairs of electrons are on the central Se atom? H3O + ion - - How many lone-pairs of electrons are on the central O atom? SeO2 molecule - - How many lone-pairs of electrons are on the central Se atom?

What is the name of the scientist who discovered the electron? a. Niels Bohr b. John Dalton c. J. J. Thompson d. Robert Millikan

Cell structures Drag the tiles into the correct box. Only in animal cells

Attempt 2 A sample of gas contains 49.16 % N 2 gas, 19.85 % Br 2 gas, 9.95 % CO 2 gas, and 21.04 % of an unknown gas. The average atomic mass of the gas mixture is 50.71 u. Calculate the atomic mass of the unknown gas.

A chemist determined by measurements that. 040 moles of gold participated in a chemical reaction. calculate the mass of gold that participated in the chemical reaction. round your answer to significant digits.

10) A screwdriver has the density of 5.5 grams per cubic centimeter. It also has the mass of 2.3 grams. What is the screwdriver's volume?

A chemist weighed out 20.7 g of sodium. Calculate the number of moles of sodium she weighed out

If 1.00 mol of argon is placed in a 0.500-L container at 20.0 ∘C, what is the difference between the ideal pressure (as predicted by the ideal gas law) and the real pressure (as predicted by the van der Waals equation) ? For argon, a=1.