** *im so stuck on this test i dont understand any of it* which statement is a correct statement for the law of conservation of mass? a. the total mass decreases during a chemical reaction b. the total mass increases in a chemical reaction c. the total mass remains the same during a chemical reaction d. the total mass is unpredictable in a chemical reaction which element(s) are not balanced in this equation? fe2o3+3 co -> fe+3 co2 a. only the o is unbalanced b. c and o are bothe unbalanced c. fe and o are both unbalanced d. only the fe is unbalanced

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)

Consider the following reaction at equilibrium. 2co2 (g) 2co (g) + o2 (g) h° = -514 kj le châtelier's principle predicts that the equilibrium partial pressure of co (g) can be maximized by carrying out the reaction a. at high temperature and high pressure b. at high temperature and low pressure c. at low temperature and low pressure d. at low temperature and high pressure e. in the presence of solid carbon

‘which reaction would most likely require the use of an inert electrode?