In which era did the first fish appear?

a. Carboniferous

b. Paleozoic

C. Mesozoic

d. Permian

Is it possible to decrease resistance of the wire without changing the material it's made out of?

At 0°C, frozen water (ice) changes to liquid water. When an ice cube is placed on something that is warmer than it, heat will move from the warmer substance to the water until A. both objects are the same temperature. B. the ice melts. C.

The half-life of radium-226 is 1600 years. How many grams of a 0.25 g sample will remain after 4800 years?

Something with a density greater than 1.00 g ml

What ion must be produced when an acid dissolves in water?

What is the biggest difference between an exothermic and endothermic process? A. The direction of energy flow. B. The amount of energy transferred. C. The type of energy being transferred. D. The speed with which energy is transferred.

The mass of 1 mol of chromium (atomic mass 51.996 amu) is

Which of the following elements will tend to form a cation? A. Oxygen B. Nitrogen C. Sulfur D. Lead E. All of the Above

Is pure orange juice a solution or a suspension

If a catalyst is used in a reaction: a. the energy of activation increases. b. the reaction rate does not change. c. the reaction rate increases. d. the equilibrium shifts.