Class 10 Science Chapter 5 MCQ

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

Metallic character increases down a group and decreases along a period. Thus, metallic character increases in the order Be, Mg, Ca as they belong to same group.

All the elements of a group of the periodic table have the same number of valence electrons. e.g., all the elements of group 1 have one valence electron each in their atoms. All the elements of group 18 have 8 valence electrons each in their atoms, except helium which has only 2 valence electrons in its atom. All the remaining three properties increase down the group. Note: On moving down in a particular group of the periodic table, the number of valence electrons in the elements remains the same. All the remaining three properties increase down the group.

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.

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

Gallium has a valency of 3. Hence, it forms an oxide having molecular formula E2O3. In other options, valency of E is not 3. Note: Eka-Aluminium (first element after Aluminium) i.e. gallium lies in group III of the Mendeleev’s periodic table.

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

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.

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.

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.

All the elements of a group of the periodic table have the same number of valence electrons. e.g., all the elements of group 1 have one valence electron each in their atoms. All the elements of group 18 have 8 valence electrons each in their atoms, except helium which has only 2 valence electrons in its atom. All the remaining three properties increase down the group. Note: On moving down in a particular group of the periodic table, the number of valence electrons in the elements remains the same. All the remaining three properties increase down the group.

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

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].

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

The elements with atomic numbers 57 to 71 are called lanthanide series (because their first element is lanthanum). And the elements with atomic numbers 89 to 103 are called actinide series (because their first member is actinium).

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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.

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.

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

Newlands’ law of octaves was applicable only to lighter elements having atomic masses upto 40 u i.e., upto calcium. After calcium, every eighth element did not possess properties similar to that of the first element.