If an atom has 12 protons, 13 neutrons, and 10 electrons, what is its mass number?

What stress will shift the following equilibrium system to the left? n2(g) + 3h2(g) ⇌ 2nh3(g) adding more n2(g) adding more nh3(g) increasing the pressure of the system reducing the volume of the container

Sulfuric acid (a component of acid rain) reacts with limestone (calcium carbonate) to produce calcium sulfate and carbon dioxide. this damages buildings and statues made of limestone. which solution of sulfuric acid will damage these structures more quickly? a. 0.001% b. 0.005% c. 0.010% d. 0.015%

As we move from left to right across the periodic table, what is the general trend? a) atomic radii increase. b) electronegavitiy decreases. c) nuclear shielding increases. d) metallic character decreases.