Half life

The half life of Cl is 9.5 x 10(exponent 12)s. How many atoms of Cl are present in a sample with an activity of 1.5 x 10(exponent 9) atoms/s a. 2.1 x 10(exponent 22) atoms b. 6.3 x 10(exponent 3) atoms c. 4.9 x 10(exponent negative 23) atoms d. 1.4 x 10(exponent 22) atoms e. 7.0 x 10(exponent 23) atoms

Decay

Pu decays by alpha emission. The isotope's half-life is 2.4 x 10(exponent 4) yr. How many alpha particles are emitted per second by 25mg of Pu?

Nuclear reactions

In spontaneous nuclear reactions: a. the products weigh less than the reactants b. the products weigh more than the reactants c. the difference in mass between reactants and products is zero d. mass is converted to light e. the products move at the speed of light squared

Empirical formula

A 1.000g sample of an unknown hydrocarbon containing only carbon and hydrogen is burned in excess oxygen to yield carbon dioxide and water. The masses of CO2 and H2O are 2.994g and 1.635g, respectively. What is the empirical(simplest) formula for this compound?

Bonds

1.) How many bonds are present in propene, C3H6? 2.) How many bonds are present in acetylene, C2H2?