Which of the following geographical features acted as a natural defense for Egypt against enemies from the south? A. the Nubian desert B. the Mediterranean Sea C. the cataracts of the Nile D. the black silt on the river banks Please select the best answer from the choices provided A B C D

What kind of ion is contained in salts that produce an acidic solution? a positive ion that attracts a proton from water a positive ion that releases a proton to water a negative ion that attracts a proton from water a negative ion that releases a proton to water

Hot air balloons float in the air because of the difference in density between cold and hot air. in this problem, you will estimate the minimum temperature the gas inside the balloon needs to be, for it to take off. to do this, use the following variables and make these assumptions: the combined weight of the pilot basket together with that of the balloon fabric and other equipment is w. the volume of the hot air inside the balloon when it is inflated is v. the absolute temperature of the hot air at the bottom of the balloon is th (where th> tc). the absolute temperature of the cold air outside the balloon is tc and its density is ďc. the balloon is open at the bottom, so that the pressure inside and outside the balloon is the same. as always, treat air as an ideal gas. use g for the magnitude of the acceleration due to gravity.

The is a particle with one unit of positive charge a. proton b. positron c. electron d. nucleus awnser quick it is a important science test!