Exercise 21. a maths teacher bought 40 calculators at $8.20 each and a numberof other calculators costing $2.95 each. in all she spent $387.how many of the cheaper calculators did she buy?

Harvey kept a balloon with a volume of 348 milliliters at 25.0˚c inside a freezer for a night.  when he took it out, its new volume was 322 milliliters, but its pressure was the same.  if the final temperature of the balloon is the same as the freezer’s, what is the temperature of the freezer? the temperature of the freezer is  kelvins.

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

Water is initially present in a state where its molecules are far apart. during a change of state, its molecules slow down. which change of state has most likely taken place? from a gas to a liquid from a liquid to a gas from a solid to a liquid from a gas to a plasma