12. The combined gas law states that pressure and Kelvin temperature of a fixed amount of gas are __ proportional to each, and pressure is __ proportional to the volume of the gas. a) inversely, directly c) directly,exponentially b) inversely, exponentially d) directly inversely 13. Avogadro's Law states that: a) Equal volumes of gases under the same conditions of temperature and pressure contain equal number of molecules b) The size or mass of a particle has no effect on molecules since the distances between the particles are so small c) The molar volume of any gas at STP is 22.4 L d) Pressure is directly proportional to the number of atoms or molecules 14. To find the density of a gas the following equation can be used: a) d=(PV)/(RT) C) d=(PM)/(VnRT) b) d=(RM)/(PT) d) d=(PM)/(RT)

Let's address each question one by one:12. The combined gas law is expressed as , where is pressure, is volume, and is temperature in Kelvin. According to this law:- Pressure is directly proportional to temperature when volume is constant.- Pressure is inversely proportional to volume when temperature is constant.Therefore, the correct answer is:d) directly, inversely13. Avogadro's Law states that equal volumes of gases, at the same temperature and pressure, contain an equal number of molecules. This is a fundamental principle of gas behavior.The correct answer is:a) Equal volumes of gases under the same conditions of temperature and pressure contain equal number of molecules14. To find the density of a gas, we use the ideal gas law equation rearranged for density. The formula for density ( ) is derived from and is given by: where is pressure, is molar mass, is the ideal gas constant, and is temperature in Kelvin.The correct answer is:d)