Saturday, 8 February 2020

PLUS ONE CHEMISTRY QUESTIONS AND ANSWERS

Chapter 3
            ELEMENTS AND  PERIODICITY IN                                             PROPERTIES

1. Considering elements B,Al,Mgand K .The correct order of their metallic character is .................
Ans:-    k>Mg>Al>B

2. In the modern periodic table, the period indicates the value of
a. Atomic number
b. Atomic mass
C. Principal quantum number
d. None

Ans:- principal quantum number

3. Which of the following statement related to the modern periodic table is incorrect
a. The p- block has 6columns , because a maximum of 6 electrons can occupy all the orbital in a p shell
b. The d block has 8 columns , because maximum of 8 electron can occupy all the orbital in a d shell.
C. The block indicates the value of azimuthal quantum number for the last sub shell that recieved electrons in building up electronic configuration
Ans : b

4. Anything that influences the valence electrons will affect the chemistry of the element.  Which one of the following factors does not affect the valence shell?
a. neclear charge
b. nuclear mass
c. Number of electrons
d.atomic mass

Ans:- nuclear mass

5. " Among halogen,  the currect order of energy released in  electron gain is F>cl<Br>l  " state whether this statement is true or False

Ans:- False, correct order is F<Cl>Br>

6. The size of isoelectronic species F, Ne and nat is affected by
a. Nuclear charge
b. Valence principal quantum number
c. Electron- electron intersection in outer orbital
d. None
Ans:-
a and c

7. Which one of the following statement is incorrect in relation to ionisation enthalpy?

a. Ionisation enthalpy increases for each successive electron
b. The greatest increases ionisation enthalpy is experienced on removed of electron for core noble gas configurations
c.The remove of electron for orbitals bearing lower value is easier then from orbital having higher n value
d . None of thus

Ans:- c

8. Observe the relationship between the first two terms and fill in the blanks
a. Electron gain enthalpy : F<Cl>Br>
b. ....................: O>F>N>Cl

Ans: chemical reactivity in terms of oxidation property

9. Which of the following is the correct order of size of the given species ?
a. |>|- >|+
b. |+ >|->|
c. |>|+>|-
d. |->|>|+

Ans :-   d

10. The elements in which electron are progressively filled in 4f - orbital called
Ans:- Lanthenoids

11. Atomic number of two elements A and B are 31 and 41. Identify their group and period in the long from of the period periodic table

Ans:- Element A 31; valence electronic configuration 4s2 4p1;  group -13and period -4 Element B : 41; valence electronic configuration 4d4 5s1, group- 5 and period-5

12. Periodic table is a chart in which elements having similar chemical and physical properties are grouped together

a. Group the following elements in pairs that you would expect so show similar chemical properties k, F, O,  Na, Cl, S
b. Out of  Fe2+ and Fe3+ ions  which is smaller in size? Explain.

Ans:-
a. K and  Na , F and Cl, O and S
b. Feat is smaller than feat grater the charge smaller will be the ion

13.Develepment of periodic table and periodic law are the consequence of  systematicsing knowledge of elements
a. State the morden periodic law
b  of the following which scientists did not contribute towards development of periodic table

I. Dobereiner
ii. Boyle
iii. Lother Meyer
iv. Newton's

Ans ;-
a. Morden periodic law  state that the physical and chemical properties of the elements are periodic function of the atomic number. 
b. Boyle

14.  Generally electron gain enthalpy increases along a period and decreases down the group.  But electron gain enthalpy of oxygen is - 141 kJ/mol while that of sulfur is - 200 kJ/mol explain

Ans:- This is because when an electron is added to zero,  the electron goes to smaller n= 2 level and suffers electron - electron repulsion where as in sulfur, the electron occupies a large n= 3 level and electron- electron repulsion  is less

15.k+and Ca2+ are isoelectronic with argon
a. Explain what is isoelectronic in
b. Out of  Nat and Na+ which has smaller - size and why? K+
Ans:-
a. The ions having same number of electrons but different magnitude  of nuclear charge are called  isoelectronic ion b
b. ( Nahas smaller size then Na the radius of cation is smaller than that of the parent atom




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