Modern periodic table consists of 7 horizontal rows known as periods and 18 vertical columns named as groups.
B. What is the other name for group 18 th elements?
Answer: 1
Noble gases are the names given to group 18 elements because they rarely interact with other elements and are very stable due to having the most valence electrons that their outermost shell can support.
C. Which of the following elements in group 17 is the most reactive?
Answer: 3 Fluorine
Explanation: The size of the atoms of elements continues to grow as we descend in a group. Fluorine is the smallest element and has the greatest tendency to gain an electron to complete its octet because it occupies the top position in the halogen group. As a result, the element fluorine in group 17 is the most reactive.
D. Which element’s melting point is the highest?
Answer: (1) Silicon
Silicon is a non-metal. It also has a substantial covalent bond. As a result, the structure’s strong covalent bonds must be broken with a lot of energy. Silicon has a high melting point as a result.
E. What modifications did early 1900s chemists make to Mendeleev’s periodic table?
Answer: 4
F. In what order does the metallic character appear in the group?
Answer: 2
As you move down a group, the metallic quality gets stronger. The ability of metals lower in a group to lose electrons increases as the ionization energy decreases going down a group (or increases going up a group), making them more reactive.
G. Which of the following best describes the correct order of oxygen, fluorine, and nitrogen’s atomic radii?
Answer: 3 (F < O < N)
In the order of nitrogen, oxygen, and fluorine on the periodic table, oxygen (8), fluorine (9), and nitrogen (7) all belong to the same period. The atomic radius of the elements now decreases when moving from left to right over a while. Therefore, nitrogen has the largest atomic radius.
H. Which of the following elements has two shells, both of which are filled completely?
Answer: 2 (Neon)
Neon with an atomic number of 10 has 2 electrons in the s-subshell and 8 electrons in the p-subshell.
I. The elements that do not normally form compounds are:
Answer: 4
Inert gases are in octet state and hence they don’t react normally.
J. Which of the following does not decrease as one descends the group of the periodic table?
Answer: 4 (the valence electrons)
The number of valence electrons in a group stays constant
K. What happens to an element’s electropositive nature as it moves from the left to the right in a periodic table?
Answer (2) Decreases
The ability of an element to lose electrons and form positive ions defines it as having an electropositive property. The nuclear charge is now increasing as the periodic table moves from left to right due to the gradually increasing number of protons, which causes the nucleus to pull the valence electrons more strongly. Moving from left to right in a periodic table results in a decrease in the electropositive character of elements because it becomes increasingly difficult for atoms to lose electrons.
L. A lithium atom has 3 protons, 3 neutrons, and 3 electrons. Which of the following sets of particles represents an isotope of this atom?
Answer: 4
Lithium’s atomic number is always 3, and its atom always has three protons. However, the mass number in the isotope with 3 neutrons is 6 and in the isotope with 4 neutrons is 7. There are only a few isotopes in nature. Lithium, for example, has isotopes with 3 and 4 neutrons, but neither an isotope with 2 nor an isotope with 5 neutrons exists.
M. Transition metals refer to which group of elements?
Answer: (c) Group number 3 to 12
Because they are metallic elements that bridge the gap between the main group elements, which are found in groups 1 and 2 on the left side of the periodic table, and groups 13–18 on the right, the elements in groups 3–12 are known as transition metals.
N. The periodic table’s groups 2, 14, and 16 are home to the elements A, B, and C, respectively. What element will create covalent bonds between the two others?
Answer: (2) B and C
The sharing of electrons between two atoms creates a covalent bond. To complete the octet of each included atom, the element B (which belongs to group 14) can share its four valence electrons with two elements of the C type (from group 16).
O. Which of the following options best represents the correct order of electronegativity?
Answer: (4) Li > Na > K = Rb > Cs
The ability of an atom in a chemical compound to draw shared electrons to itself is measured by its electronegativity. Li, Na, K, Rb, and Cs have electronegativities of 1, 0.9, 0.8, 0.8, and 0.7, respectively.
P. Li, Mg, and Be, Al- the relationship are known as the _ relationship.
Answer: (2) Diagonal Relationship
In the case of the formation of various compounds with a similar composition, the elements Li and Mg, Be and Al are comparable to one another. According to their placement in the periodic table, they are said to be in a diagonal relationship because they behave somewhat similarly to one another.
Q. An element M is in group 13 th of the periodic table, the formula for its oxide is
Answer: (2) M2O3
The oxygen atom (with two valence electrons) has a 2 oxidation state, whereas the element M, which is in group 13 of the periodic table, can have a +3 oxidation state. Therefore, M2O3 is the formula for the corresponding oxide.
R. With which of the following does boron exhibit a diagonal relationship?
Answer: 1
As they are similar to lithium in group 1 and magnesium in group 2, boron in group 13 and silicon in group 14 have a diagonal relationship. There are numerous traits that both boron and silicon share.
S. Considering the hydration enthalpy, which of the following orders is correct?
Answer: 2
The correct order of hydration enthalpies is given as Be +2 > Mg +2 > Ca +2 > Sr +2 > Ba +2 , and the hydration enthalpies of alkaline earth metal ions are greater than the size of alkali metal ions. Thus, the hydration enthalpy decreases with the increase in ionic size along with the group towards down. We can conclude these are significantly more hydrated than them.
T. The period number is matched to the highest value of the following quantum numbers:
Answer: 4
The horizontal rows that depict period number represent the highest principal quantum number of the atoms in the period, as can be seen in the most practical and widely used version of the long-form periodic table, known as the modern version.
U. Which of the following statements about the acidic character is accurate?
Answer: 1
Lewis acids are how the halides of group 13 elements behave. Boron, aluminum, gallium, and indium are in the correct order of decreasing acidity. Chlorine, bromine, and iodine are considered halides in this context, whereas thallium trichloride can only be used as an oxidizing agent because it decomposes quickly.
V. What compound is employed in the calibration of ultraviolet light?
In addition to being useful in UV, potassium dichromate (K2Cr2O7 ) is most useful in the visible spectrum. Potassium dichromate itself is stable and available in high purity. It has a linear response, good temperature stability, and is stable as a solution in diluted perchloric acid solution.
W. In relation to halogens, which statement is true?
Answer: 3
All halogens are diatomic and produce ions that are one type only. Except for fluorine, all halogens have more than one stable oxidation state and can function as both oxidizing and reducing agents. As a result, statement option 3 is correct.
X. With the formula XCl2, element X creates a solid with a high melting point known as a chloride. The Periodic Table would most likely place X in the same group as
Answer: (2) Magnesium
The atoms of group two alkaline earth metals each have two valence electrons. They can give two additional chlorine atoms their two valence electrons to create solid compounds of the form XCl2.
Y. Which of the following is true about neutrons?
Answer: 1
The mass of one nucleon is roughly equal to one amu (also known as an atomic mass unit) (either proton or neutron). The term “amu” refers to the average mass of one proton and one neutron, which is roughly equivalent to 1.67 *10 24 g.
Z. Which of the following conditions would increase the yield of ammonia production from the Bosch-Haber process?
Answer: 4
Since the forward reaction is exothermic (N2 + 3H2 → 2NH3), low temperatures would increase the rate of reaction, producing more ammonia. This is in accordance with the Le Chatelier’s principle. High pressures will also speed up the reaction because there are fewer molecules overall on the product side.
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