Related InterviewSolutions

• Choose from the following : `""_(20)Ca,""_(3)Li, ""_(11)Na, ""_(10)Ne` (i) An element having two shells completely filled with electrons. (ii) Two elements belonging to the same group in the periodic table.
• Which among the following elements has the largest atomic radii ?A. NaB. MgC. KD. Ca
• Which element has (a) two shells, both of which are completely filled with electrons?(b) the electronic configuration 2, 8, 2? (c) a total of three shells, with four electrons in its valence shell? (d) a total of two shells, with three electrons in its valence shell?(e) twice as many electrons in its second shell as in its first shell?
• Which of the following elements would lose an electron easily ?A. MgB. NaC. KD. Ca
• Which of the following elements does not lose an electron easily ?A. NaB. FC. MgD. Al
• An atom has electronic configuration 2, 8, 7. (a) What is the atomic number of this element? (b) To which of the following elements would it be chemically similar? (Atomic numbers are given in parentheses.) N(7) F(9) P(15) Ar(18)
• An element has electronic configuration 2, 8, 3. What is the atomic number of the element ? To which (i) group and (ii) period does this element belong ?
• Name the members of alkaline earth family. Which out of them is radioactive in nature ?
• Arrange giving reason the following elements in increasing order of their atomic size : (a) Be, O, F (Given that they beiong to 2nd, 16th and 17th groups respectively and to 2nd period). (b) I, CI, F (Given that they belong to 5th, 3rd and 2nd periods respectively of 17th group). (c) Mg, N, P (Given that Mg and P belong to `2^(nd)" and "15^(th)` group respectively of `3^(rd)` period and N belongs to `15^(th)" group of "2^(nd)` period).
• Shailesh lies in a bigh industrial city having a large number of chemical industries onits outskirts. This city has also a very heavy traffic density. There is a big lake in the middle of this city which has much less water left init but the lake has still a large number of fish in it. During the last one and a half months, there ha been to much rain in the city with the pH of rain water being about 5.5. One day people found that many fish in the lake ha died. No one knew the reason for the death of fish in the lake or how the death of remaining fish in the lake could be prevented. Shailesh, who is a student of class X could understand the reason for the death of fish in lake. He also suggested an immediate solutioin for the prevention of death of more fish in the lake water. (a) What conclusion do you draw the fact that the rain water has a pH of about 5.5? What name is given to such a rain? (b) What makes the pH of rain water to be about 5.5? (c) What happens to lake water when too much rain water haivng pH of 5.5 collects in it? (d) Why have the fish died after the heavy rains? (e) Why suggestion do you think has been made by Shailesh to prevent the death of more fish in the lake? Why (f) What values are displayed by Shailesh in this episode?