Which of the following is a compound?
a. iron
b. lead
c. helium
d. methane

8.98 dm3 of hydrogen gas is collected at 38.8 °c. find the volume the gas will occupy at -39.9 °c if the pressure remains constant.

Consider the reduction reactions and their equilibrium constants. cu+(aq)+e−↽−−⇀cu(s)pb2+(aq)+2e−↽−−⇀ pb(s)fe3+(aq)+3e−↽−−⇀fe(=6.2×108=4. 0×10−5=9.3×10−3 cu + ( aq ) + e − ↽ − − ⇀ cu ( s ) k =6.2× 10 8 pb 2 + ( aq ) +2 e − ↽ − − ⇀ pb ( s ) k =4.0× 10 − 5 fe 3 + ( aq ) +3 e − ↽ − − ⇀ fe ( s ) k =9.3× 10 − 3 arrange these ions from strongest to weakest oxidizing agent.

In science class richard learns that a substance has a boiling point of 230 fahrenheit his teacher ask him to convert this temperature to degrees celsius what is the boiling point of his substance in degrees celsius