The period of an element is the amount of time is it takes for half of radioactive isotope to decay. true or false? If false, make a statement true

1. What is the amount of energy required to raise the temperature of 150 grams of aluminum by 10°C? A. 0.897 J B. 13.45 J C. 1345.5 J D. 4.18 J 2. If you have an endothermic reaction, heat energy is written on the product side of the equation.

Toluene, C7H8, is used in the manufacture of explosives such as TNT (trinitrotoluene). A 1.500 g sample of liquid toluene was placed in a bomb calorimeter along with excess oxygen.

Which of the following is an example of voluntary muscle action? A) fingers typing on a keyboard B) pupils dilating in reaction to light C) the heart pumping blood through the body D) the stomach moving food to the intestines

A chemist dissolves 156. mg of pure hydrobromic acid in enough water to make up 220. mL of solution. Calculate the pH of the solution. Be sure your answer has the correct number of significant digits.

Which statement is true for a pure compound but NOT true for a pure element?

A base a. causes phenolphthalein indicator to change from colorless to pink. b. donates a proton in a proton transfer reaction. c. accepts electrons in an electron transfer reaction. d. produces hydrogen ions in solution. e. does none of the above.

Which of these is an indicator that a chemical reaction has occurred? precipitate forms temperature remains the same color is diluted mass increases

The half-life of isotope X is 3 days, how long will it take for one half of 10g sample to decay

A 69.1-g sample of h2o contains how many molecules of water?

Why is ac used instead of dc