How i know a chemical reaction took place

Will mark brainliest if correct/available! which of the following statements is true? all plants need flowers to sexually reproduce. sexually reproduced offspring are identical to their parents. fertilization always occurs inside the female's body. a body cell has twice the number of chromosomes as an egg cell.

Which of the following is true? a. under the current unemployment insurance system, benefits replace about 90 percent of the typical worker's prior pretax earnings. b. high benefit payments to unemployed workers will tend to increase the rate of unemployment. c. if a system of personal savings accounts replaced the current unemployment benefit system, the unemployment rate would fall to zero. d. the rate of unemployment in the large european economies has been persistently lower than that of the united states due to their more generous unemployment benefits.

The presence of iron oxides in rocks, formed during a specific time period, can be used as evidence of oxygen in the atmosphere during that time period. question 18 options: true false