Explanation:
Add 273 to the temperature in Celsius to convert it to Kelvin. −185∘C+273 = 88K. The rest of the choices are incorrect.

Explanation:
Electron configuration of the $\mathrm{Cr}$ atom is [Ar] 4s13d^5.
The loss of one s and two d electrons results in [Ar] 3d^3 configuration.

Explanation:
Relative atomic mass of Br=(0.5069)(78.92)+(0.4931)(80.92)=79. The rest of the choices are incorrect relative atomic masses of bromine.

Alternative Method:

79Br atomic mass can be rounded up to 79

81Br atomic mass can be rounded up to 81

Since the relative abundance of both isotopes is about 50% each, the relative atomic mass of Bromine should be close to 80. Choice D corresponds to that estimation.

Explanation:
At high pressures and very low temperatures, the inter-particle forces strengthen, spaces between particles decrease causing the deviation from ideal gas behaviour PV/nRT > 1.

Explanation:
Successive ionization energies are larger, as electrons are removed, there is less electron-electron repulsion, so the remaining electrons are pulled closer to the nucleus, and more energy is required to remove them.

Explanation:
To answer this question, the student must understand the properties of the mixture's components.
The wood chips would not dissolve in the water, so they are filtered out first. This will leave the sodium chloride dissolved in the water. The water can be evaporated to remove the water (to isolate the salt).
Paper chromatography would be ineffective in this scenario as it is used for separating substances such as dyes, pigments, and proteins.
This question is categorized as medium complexity because the student must understand the properties of matter and separation techniques.

Explanation:
The lines converge as energy levels increase (increased distance from the nucleus).
Higher energies result in higher frequencies.

Explanation:
The s orbital has a spherical shape. In terms of energy, s has the lowest, followed by p and d orbital. Thus, Choices A, B, and D are all incorrect

Explanation:
The $\mathrm{n}$ atom and Mn^2+ ion have the following orbital diagrams:

The valence electrons and the two lost in the 2+ ion are the $4s$ electrons so the unpaired electrons remain 5.

Explanation:
Seawater is a mixture of water and salts. Sucrose, distilled water, and sodium chloride are all examples of compounds.

Explanation:
Choice A is incorrect because the orbital diagram does not satisfy Hund's rule wherein all orbitals must be singly occupied before pairing.
Choice B is incorrect because Pauli's Exclusion principle is not obeyed by having two electrons with the same spin in one orbital.
Choice C is correct because, according to Hund's rule, the orbitals must be half-filled first before pairing, and the paired orbital must have electrons in an opposite spin.
Choice D is incorrect because the 2s orbital must be filled first before filling the 2p orbital, as illustrated by Aufbau's Principle.

Explanation:
Second ionization energy is the energy required to remove one mole of electrons from one mole of singly positive gaseous ions.

Explanation:

Isotopes with fewer neutrons will have a lower density

Explanation:
There is an inverse relationship between frequency and wavelength. If the wavelength is doubled, the frequency will decrease by half. Therefore, Choices A, C, and D are all incorrect.

Explanation:
Second ionization energies are higher than the first as the electrons are being removed from a positive ion resulting in a stronger electrostatic attraction.
First ionization energies do increase across a period due to increasing nuclear charge.
First ionization energies also decrease down a group due to increased shielding (number of shells).

Explanation:
Based on the balanced chemical equation, the number of moles of NO2 is twice that of N2O4. Avogadro's law states that the volume of a gas is directly proportional to the number of moles of the gas present (25/2= 12.5).

Explanation:
According to Aufbau’s principle, the arrangement of subshell in increasing energy is 1s 2s 2p 3s 3p 4s 3d 4p. Therefore, Choices A and B are both incorrect. Choice C is incorrect because 2d does not exist.

Explanation:
Choice A is the correct answer because it satisfies Aufbau's principle and the number of electrons in the electron configuration aligns with the same number of electrons in the orbital diagram.

The atomic number is the number of protons. The mass number is the sum of the number of protons and neutrons. For a neutral atom, the number of electrons is equal to the number of protons.

Explanation:
Condensation (gas to liquid) requires making bonds and therefore, releases energy. Sublimation (solid to gas) requires breaking bonds and therefore absorbs energy.

Explanation:
Liquids have an indefinite shape (take the shape of the container) but have a definite volume. Choice A describes solids. Choices B and D describe the characteristics of gases.

Explanation:
1 mole is the number of H2 molecules in 2.02 g of H2. Choices A, B, and C all conform to the definition of a mole