Does altitude has an effect on weight? PLEASE HELP!​

Awelder using a tank of volume 7.50×10^-2 m^3 fills it with oxygen (with a molar mass of 32.0 g/mol ) at a gauge pressure of 3.30×10^5 pa and temperature of 37.1 ∘c. the tank has a small leak, and in time some of the oxygen leaks out. on a day when the temperature is 23.1 ∘c, the gauge pressure of the oxygen in the tank is 2.00×10^5 pa . a) find the initial mass of oxygen. b) find the mass of oxygen that has leaked out.

How many milliliters of water at 23 °c with a density of 1.00 g/ml must be mixed with 180 ml (about 6 oz) of coffee at 95 °c so that the resulting combination will have a temperature of 60 °c? assume that coffee and water have the same density and the same specific heat. how much will the temperature of a cup (180 g) of coffee at 95 °c be reduced when a 45 g silver spoon (specific heat 0.24 j/g °c) at 25 °c is placed in the coffee and the two are allowed to reach the same temperature? assume that the coffee has the same density and specific heat as water. a 45-g aluminum spoon (specific heat 0.88 j/g °c) at 24 °c is placed in 180 ml (180 g) of coffee at 85 °c and the temperature of the two become equal. (a) what is the final temperature when the two become equal? assume that coffee has the same specific heat as water. (b) the first time a student solved this problem she got an answer of 88 °c. explain why this is clearly an incorrect answer.

How much heat is needed to raise the temperature of 5g of water by 16°c?