Class 10 Science Chapter 5 MCQ

Due to large positive charge on the nucleus, the electrons are pulled in more close to the nucleus and the size of the atom decreases. However, the size of atom of an inert gas is bigger than that of the preceding halogen atom. The greater size of the inert gas atom in a period is due to the structural stability of its outermost shell consisting of an octet of electrons. Note: As we move from left to right in a period, the atomic number of elements increases which means that the number of protons and electrons in the atoms increases (the extra electrons being added to the same shell.

Here, all the statements are correct. Hence, your answer will be option [D].

Newlands divided the elements into horizontal rows of seven elements. In 1864, Newlands arranged the then known elements in the order of increasing atomic masses and found that the properties of every eighth element are similar to the properties of the first element. Based on this observation, Newlands gave his law of octaves for the classification of elements.

Its outermost shell has 4 electrons. So, it is a non-metal. Non-metal forms acidic oxide and by sharing of electrons with halogen, it forms covalent halide. Note: Atomic number 14 has electronic configuration 2, 8, 4.

Non-metals can form acidic oxides in general. Non-metals have 4 to 8 electrons in the outermost shell. The electronic configuration of given elements are (a) i.e. 7 = 2, 5 (b) i.e., 3 = 2, 1 (c) i.e., 12 = 2, 8, 2 (d) i.e., 19 = 2, 8, 8, 1. So, element with atomic number 7 (electronic configuration 2, 5) with is non-metal (N) and it will form an acidic oxide. Rest three elements atomic numbers, 3 (Li), 12 (Mg) and 19 (K) are metals and hence form basic oxides.

Here, all the statements are incorrect. Hence, your answer will be option [D].

Here, all the statements are incorrect. Hence, your answer will be option [D].

If two (or more) elements have the same number of valence electrons, then they belong to the same group of the periodic table. For example, if two elements have electronic configurations of 2, 8, 1 and 2, 8, 8, 1, then they have the same number of valence electrons (1 valence electron each), and hence they belong to the same group of the periodic table.

The first period starts with hydrogen and ends with noble gas helium. All other periods start with alkali metals like lithium, sodium, potassium, etc., and end with noble gases like neon, argon, krypton, etc.

Electronic configuration of Mg (atomic number 12) 2, 8, 2. Electronic configuration of Na (atomic number 11) 2, 8, 1. Electronic configuration of K (atomic number 19) 2, 8, 8,1. Electronic configuration of Ca (atomic number 20) 2, 8, 8, 2. From the above electronic configurations, it is clear that K and Na will lose electron easily to achieve stable configuration. But out of K and Na, K will lose electron more easily because the force of attraction on valence electron of K is least among the given. In other words, larger the atomic radius of an element more easily it can lose its valence electron. Among all these, K has the largest atomic radius, therefore it can lose its valence electron more easily.

As we move from left to right in a period, the atomic number of each succeeding element increases by 1. So, the electrons are attracted close to the nucleus and hence, the atomic size decreases, along a period from left to right. Therefore, the increasing order of radii is F, O, N as atomic number of F, O and N are 9, 8 and 7 respectively. Due to which F belongs to 17th group. O belongs to 16th group and N belongs to 15th group. Note: Atomic radii is the distance between the centre of the nucleus and the outermost shell which contains electrons in an isolated system.

Thus, Na (group 1) has one, Al (group 13) has three (13-10), Si (group 14) has four (14-10) and P (group 15) has five (15-10) valence electrons. Therefore, P has maximum number of valence electrons i.e., 5 (maximum among the given). Note: Amongst representative elements, the number of valence electrons increases as the group number increases from left to right.

Here, all the statements are correct. Hence, your answer will be option [D].

The elements of 2nd period involve the filling of 2nd shell i.e. L shell. Because in periods 2, there are two shell, K and L.

Constituent of all organic compounds is carbon. It belongs to group 14.

Element with electronic configuration 2, 8, is an inert gas i.e., neon and hence, belongs to group 18. Note: Group 18 elements are known as noble gases or inert gases. They are helium, neon, argon, krypton etc. All the noble gases have 8 electrons in their outermost shell (except helium which has only 2 electrons) in the K valence shell. Thus, the valence shells of all the noble gases are completely filled with electrons.

Here, all the statements are correct. Hence, your answer will be option [D].

The first period starts with hydrogen and ends with noble gas helium. All other periods start with alkali metals like lithium, sodium, potassium, etc., and end with noble gases like neon, argon, krypton, etc.

2nd period contains elements with atomic number 3(Li), 7(N), 10(Ne). Since, 2nd period has elements having atomic number 3 to 10. Note: The number of elements in any period is fixed by the maximum number of electrons that can be accommodated in that particular shell. The maximum number of electrons that can be accommodated in any shell is given by the formula 2n2 where, n is the number of the given shell starting from the nucleus.

Modern Periodic table has 18 vertical columns, known as groups and 7 horizontal rows, known as periods.

Here, all the statements are correct. Hence, your answer will be option [D].

The groups 1 and 2, and 13 to 17 contain the normal elements (typical elements or representative elements). Group 18 elements are known as noble gases or inert gases. They are helium, neon, argon, krypton, etc. All the noble gases have 8 electrons in their outermost shells (except helium which has only 2 electrons in the K valence shell). Thus, the valence shells of all the noble gases are completely filled with electrons.

Mendeleev’s left some gaps in the periodic table for those elements which were not known at that time. Germanium element found a place in the periodic table later and Mendeleev’s predictions were found to be remarkably correct.

Here, all the statements are correct. Hence, your answer will be option [D].

According to Mendeleev’s periodic law, the elements were arranged in the periodic table in the order of increasing atomic masses. Note: Mendeleev’s periodic law states that, the physical and chemical properties of elements are a periodic function of their atomic masses.