26 questions · timed · auto-graded
Solution: Electronic configuration of,
Na: 2, 8, 1.
Al: 2, 8, 3.
Si: 2, 8, 4.
P: 2, 8, 5.
Phosphorus has 5 valence electrons, while others have less number of valence electrons.
Solution: Elements of the same group have same number of valence electrons hence valency will remain same.
Solution: The elements B(Z = 3), C(Z = 7) and D(Z = 10) belong to the same period. It is second period.
Solution: Modern Periodic Table has 18 Groups and 7 periods. Columns are called groups, while rows are called periods.
Solution: These elements are in same group but Be is at the top, while Ca is at bottom. Metallic character increases as we move down the group.
Solution: The elements of 2nd period contain two shells; K and d L shell.
Solution: It is the correct order. These elements are present in second period.
Solution: The element potassium (K) with maximum size would lose electron easily.
Solution: Formation of acidic oxides is character of non-metals. Here element with atomic number 7 is a non-metal that is nitrogen. Rests of all are metals.
Solution: Metals can easily lose electrons and exhibit electropositive nature whereas non-metals have tendency to accept electrons and exhibit electronegative nature. Na, Al and Mg are metals whereas F is a non-metal.
Solution: Isotopes of an element have same atomic number but different atomic masses. They show same chemical properties but different physical properties.
Solution: The modern periodic table is tabular arrangement of elements in increasing order of their atomic number therefore isotopes are paced at same position.
Solution: Na and K belong to the same group. i.e. Group I. Ca and Mg belong to the Group II. The atomic radius decreases in moving from left to right along a period. This is due to an increase in nuclear charge which tends to pull the electrons closer to the nucleus and reduces the size of the atom. Hence K has largest atomic radii.
Solution: In this element, the outermost shell is completely filled. Hence, this belongs to Group 18.
Solution: Eka-aluminium is in the same group as Aluminum, i.e. Group 13. Hence, there are 3 electrons in its outermost orbit. So, it can lost 3 electrons to form a bond. Oxygen has 6 electrons in its outermost orbit which means it can gain 2 electrons to form a bond.
Solution: Law was found to be applicable upto the element calcium.
Solution: These are also called semi-metals and possess the characteristics of both metals and non-metals.
Solution: The element with atomic number (Z) = 14 is silicon (Si). It is a metalloid.
Solution: Elements A(Z = 9) and C(Z = 17) belong to the same group. It is a halogen family (group 17).
Solution: Atomic size decreases along a period. However, the noble gas atom is an exception. It has very large size.
Solution: Mandeleev named the undiscovered elements as Eka-boron, Eka-aluminium and Eka-silicon. These were replaced with scandium, gallium and germanium respectively in due course of time.
Solution: The distance between nucleus and outermost orbit is called atomic radius. In fig (iii), it is quite clear. In all other figures, the distance is not correctly shown.
Solution: These all elements belong to same period in which non-metallic characters increases from left to right.
Solution: The metallic character of the elements decreases along a period. These elements are present in third period.
Solution: Carbon is an essential element for all organic compounds and belongs to group 14.
Solution: The Mendeleev's periodic law is an arrangement of elements in increasing order of their atomic masses as Mendeleev's periodic law states that, the physical and chemical properties of elements are a periodic function of their atomic masses.
