A)    Au

B)    Ca

C)    Ba

D)    Al

Correct Answer: Option A - Au

Firstly, gold and gold oxides have very nearly the same free energy. This means that to make gold oxide gives you almost no free energy as a biproduct. Most elements have massive free energies when it comes to oxidation. It is this free energy that drives things to become compounds.

Secondly, gold has very high activation energy. This means if you want gold to react you have to make it very hot indeed. Gold will melt before it will oxidize. It is called being stable.

Thirdly, if you have magma (molten rock underground) all the metals are already up near their activation energy and are all mixed together. When things start to cool off a metal like iron, silver, zinc, copper becomes an oxide and all the free energy is released.

Hence, options B, C and D are incorrect.

A)    1

B)    2

C)    3

D)    4

Correct Answer: Option B - 2

The element having the first ionization energy of, 736 kJ/mol is Magnesium. The electronic configuration of Magnesium in ground state is as below:

1s² 2s² 2p⁶ 3s²

It has 2 valence electrons in the ground state in the 3s principal energy level.

Hence, options A, C and D are incorrect.

A)    As

B)    P

C)    N

D)    Bi

Correct Answer: Option D - Bi

From left to right across the period, metallic character decreases. But it increases going down a group (last element in a group will have the most metallic character). Bi is the last element in group 15 so it is the most metallic. Order of group 15 elements in descending rate of metallic character is: Bi(Bismuth), Sb(Antimony), As(Arsenic), P(Phosphorus) and N(Nitrogen).

Hence, options A, B and C are incorrect.

A)    CaCl₂₂

B)    CrCl₃

C)    NaOH

D)    KBr

Correct Answer: Option B - CrCl₃

Colored aqueous solutions are a characteristic of transition compounds. The only transition compound in the above choices is CrCl₃. Cr is a transition element.

Transition elements also known as transition metals, are any of the metallic elements that have an incomplete inner electron shell which serve as transitional links between the most and the least electropositive elements in a series of elements. They are colored compounds, characterized by multiple valences and the ability to form stable complex ions.

In options A, C and D Calcium (Ca), Sodium (Na) and Potassium (K) are transition elements. Hence, these options are incorrect.

A)    Sodium

B)    Phosphorus

C)    Aluminum

D)    Calcium

Correct Answer: Option B: Phosphorus

The energy needed to remove one or more electrons from a neutral atom to form a positively charged ion is a physical property that influences the chemical behavior of the atom. By definition, the first ionization energy of an element is the energy needed to remove the outermost or highest energy, electron from a neutral atom in the gas phase

Phosphorus (P) has a ionization energy of 1011.8 kJ/mol.

Incorrect Options

• Sodium - First Ionization Energy: 495.8 kJ/mol
• Aluminum - First Ionization Energy: 577.5 kJ/mol
• Calcium - First Ionization Energy: 589.8 kJ/mol

A)    Nickel

B)    Cobalt

C)    Potassium

D)    Calcium

Correct Answer: Option A - Nickel

Atomic radius is called the width of an atom, but it is not a precisely defined physical quantity, nor is it constant in all circumstances. Atomic Radius gets greater down the periodic table and gets smaller to the right in the periodic table. Going from left to right across the periodic table, the number of protons increases. The more they increase, the more they pull and attract the outer electrons from the outermost electron shell, making the atomic radius smaller.

With a radius of 124 pm (pico meter), nickel has the smallest atomic radius of the elements given.

Incorrect Options

• Cobalt: Atomic radius 125 pm
• Potassium: Atomic radius 227 pm
• Calcium : Atomic radius 197 pm

A)    Li, Mg, Ca, Kr

B)    Ba, Ag, Sn, Xe

C)    K, Mn, As, Ar

D)    Fr, F, O, Rn

Correct Answer: Option C - K, Mn, As, Ar

The metalloids are elements which have intermediate properties and cannot be classified as either metals or nonmetals. They are also referred to as semimetals.

In the Periodic Table, the location of the stepped line divides metals and nonmetals. Elements next to the left or right of this line are metalloids. This clearly lists Aresenic as a metalloid which is a part of option C.

Hence, options A, B and D are incorrect.

A)    Chlorine

B)    Silicon

C)    Sulfur

D)    Nitrogen

Correct Answer: Option A - Chlorine

Electronegativity is a chemical property that describes the ability of an atom (or, more rarely, a functional group) to attract electrons (or electron density) towards itself in a covalent bond. An atom's electronegetivity is affected by both its atomic weight and the distance that its valence electrons reside from the charged nucleus. The higher the associated electronegativity number, the more an element or compound attracts electrons towards it. It was proposed first by by Linus Pauling in 1932. Electronegativity cannot be directly measured and must be calculated from other atomic or molecular properties.

Chlorine has an electronegetivity of 3.16 on Pauling Scale

Incorrect Options

• Sulphur has electronegetivity of 2.58 on Pauling Scale
• Silicon has electronegetivity of 1.90 on Pauling Scale

A)    Zn

B)    K

C)    Fe

D)    Ag

Correct Answer: Option B - K

Electrolysis means using an electric current to separate a mixture of ions. Metals, including K, listed near the top of Periodic Table occur as compounds in nature. The pure, uncombined form of these metals results from commercial electrolysis of salt. Notice that these metals (Mg, Na, Ca, Ba, Cs, K, Rb and Li) are either alkali metals or alkaline earth metals, the most reactive metals. Au can be found in nuggets and dust.

Hence, options A, C and D are incorrect.

A)    Number of principal energy levels

B)    Atomic numbers

C)    Number of valence electrons

D)    Atomic masses

Correct Answer: Option C - Number of valence electrons

Most of the time elements in the same group have the same number of valence electrons. Valence electrons are involved in bonding and this effects how elements react and determines their chemical properties.

Incorrect Options

The atomic mass (ma) is the mass of an atom, most often expressed in unified atomic mass units.  The atomic mass may be considered to be the total mass of protons, neutrons and electrons in a single atom (when the atom is motionless).

A quantum mechanical system or particle that is bound, confined spatially, can only take on certain discrete values of energy, as opposed to classical particles, which can have any energy. These values are called energy levels. The term is most commonly used for the energy levels of electrons in atoms or molecules, which are bound by the electric field of the nucleus. The energy spectrum of a system with energy levels is said to be quantized.If the potential energy is set to zero at infinity, the usual convention, then bound electron states have negative potential energy. Energy levels are said to be degenerate, if the same energy level is obtained by more than one quantum mechanical state. They are then called degenerate energy levels.

The atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element. In an atom of neutral charge, atomic number is equal to the number of electrons.