ASAP MULTIPLE CHOICE WILL MARK BRAINLIEST What is the composition of an isotope of calcium (atomic number 20)?

19 protons, 20 neutrons, 19 electrons
21 protons, 20 neutrons, 20 electrons
20 protons, 25 neutrons, 20 electrons
22 protons, 20 neutrons, 19 electrons

Explain the relationship between forward and backward reactions in equilibrium, and predict how changing the amount of a reactant (creating a tension) will affect that relationship.

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.

When the ionic compound nabr dissolves in water, br– ions are pulled into solution by the attraction between what two particles? a. the na+ and br– ions b. the na+ ion and the negative end of a water molecule c. the br– ion and the positive end of a water molecule d. the br– ion and the negative end of a water molecule