Calculate the amount of water (in grams) that must be added to each of the following substances to produce the indicated solution. (a) 1.90 g of urea (NH2)2CO in the preparation of a 20.6 percent by mass solution: g (b) 31.1 g of MgCl2 in the preparation of a 7.2 percent mass solution: g

Initially, the balloon had 3.0 liters of gas at a pressure of 400 kpa and was at a temperature of 294 k. if the balloon is cooled to 277 k and its volume decreased to 1 l, what will the new pressure in the balloon be?

Stage in which a typical star has completely stopped fusion

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ?