Astudent was given a solid containing a mixture of nitrate salts. the sample completely dissolved in water, and upon addition of dilute hcl, no precipitate formed. the ph was lowered to about 1 and h2s was bubbled through the solution. no precipitate formed. the ph was adjusted to 8 and h2s was again bubbled in. this time, a precipitate formed. which compounds might have been present in the unknown?

Scientific evidence tells us that the cause of earths four season is the tilt of earth as it revolves around the sun. the student is instructed to illustrate this information in a science notebook. how will the student illiterate winter in the northern hemisphere?

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 ?

Two metal blocks that have slightly different temperatures are placed next to one another. after five minutes, they both have lower but equal temperatures. according to the law of conservation of energy, what  most likelyhappened? energy was created inside the blocks.energy was destroyed inside the blocks.energy was absorbed into the blocks from outside the system.energy was transferred from the warmer block to the cooler block.