It takes 700 million years for half of the amount of Uranium-235 originally in rock to turn into Lead. If a scientist measures that a sample is 6.25% Uranium-235 and 93.75% Lead, how old is the sample?

Which part of earth’s surface receives the most direct rays from the sun? a) equator b) ocean c) poles d) mountains

For the reaction c6h14(g) & longrightarrow; c6h6(g) + 4h2(g), δp(h2)/δt was found to be 2.5 x 10-2 atm/s, where δp(h2) is the change in pressure of hydrogen. determine δp(c6h14)/δt for this reaction at the same time.

In an exothermic reaction at equilibrium, what is the effect of lowering the temperature? a. the reaction makes more products. b. the reaction makes more reactants. c. the reaction is unchanged.