Which of the following demonstrates a chemical reaction of water?

Crushing a solid reactant into powder increases the surface area of the reactant, thereby increasing chemical reaction. This is because more of the reacting molecules or ions are exposed to the other reactant, which increases the chance of particles colliding and leads to more successful collisions per second.

Rationale

Electrons are subatomic particles that have relatively little mass and are negligible when calculating atomic mass. The atomic number is usually the sum of protons and neutrons in the nucleus of the atom.

This is because when a proton is emitted from an atom, the atomic mass decreases by one unit, and the atomic number decreases by one unit. The atomic mass is the sum of protons and neutrons in the nucleus, and the atomic number is the number of protons in the nucleus. Therefore, if a proton is lost, both numbers decrease by one.

Objects A and B have the same and are subjected to the same gravitational pull. However, object B falls faster than A. This is due to a greater air resistance for A than B.

The renal vein drains deoxygenated blood from the kidneys to the inferior vena cava.

A chlorine molecule contains the fewest covalent bonds among the options provided. It consists of two chlorine atoms bonded together by a single covalent bond. Compared with the other options, ammonia has three covalent bonds, methane has 4 while water has 2.

The pH scale is logarithmic, indicating that each whole number change on the pH scale represents a tenfold change in acidity or alkalinity. Therefore, a substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4.

Browning of the apple surface is due to the action of the enzyme polyphenol oxidase. Lemon juice is acidic and lowers the pH of the apple's surface. This inactivates the enzyme polyphenol oxidase, which works best at a neutral pH. This in turn reduces the browning action on the apple.

Concentration of H+ in the solution = 10 −1 M

pH= -log(10 −1)

pH= -(-1)

=1

Melanocytes are specialized skin cells that produce melanin, which is the protective skin-darkening pigment. They are found mainly in the epidermis, though they occur elsewhere, such as in the hair.