WHICH SIGN CAN SAY THAT A PHYSICAL CHANGE HAS TAKEN PLACE 1.FORMATION OF GAS
2.FORMATION OF PRECIPITATE
3.EVOLUTION OF HEAT
4.ALL THE ABOVE

Which of the following is a compound? a.carbon b.oxygen c.hydrogen d.water

The density of an unknown gas at 98°c and 740 mmhg is 2.50 g/l. what is the molar mass of the gas with work showed?

Which is a chemical property of iron? a. it forms iron oxide (rust) when exposed to moisture and air. b. it is a gray–black metal that is hard to the touch. c. it has a melting point of 2795°f (1536°c). d. it is a good conductor of heat