2599 + Interview Questions in Chemistry in Class 9 Page 19 InterviewSolution

901.	The change of a solid directly into gas is called …….. .
Answer» SOLUTION :SUBLIMATION

Discussion

902.	The change of a liquid into vapour is called ……….
Answer» SOLUTION :VAPORIZATION

Discussion

903.	The change of a solid into gas is called …… .
Answer» SOLUTION :SOLIDIFICATION

Discussion

904.	The cation present in NH_(4)OH is
Answer» `OH^(-)` `NH_(4)^(+)` `H^(+)` `NH_(3)^(+)` Answer :B

Discussion

905.	The cathode rays are produced when a gas at a very low pressure is subjected to an electric discharge .
Answer» ANSWER :T

Discussion

906.	The cathode of an electrochemical reaction involves …………………. .
Answer» OXIDATION REDUCTION NEUTRALISATION catenation Answer :B

Discussion

907.	The Catalyst used to decrease the rate of decomposition of hydrogen peroxide is ______
Answer» ANSWER :PHOSPHORICACID(`H_3PO_4`)

Discussion

908.	The bromination of acetylene gives __________ as the final product .
Answer» dibromoethane TETRABROMOETHANE tetrabromoethane dibromoethane Solution :The BROMINATION of acetylene GIVES TERA BROMO ethane.

Discussion

909.	The boiling order of boiling points of diethyl ether, acetone and n-butyl alcohol are 35^(@)C, 56^(@)C and 118^(@)C , respectively. Which one is the following correctly represents their boiling points in kelvin scale ?
Answer» 306 K, 329 K, 391 K 308 K, 329 K, 392 K 308 K, 329 K and 391 K 329 K, 392 K and 308 K. Solution :It is the correct representation of the boiling points and is obtained by adding 273 K to the GIVEN temperature.

Discussion

910.	The boiling point of ethane is, - 88^(@)C.This temperature will be equivalent to :
Answer» 285 K 288 K 185 K 361 K Answer :C

Discussion

911.	The Bohr model of an atom is given below. Analyse it and find out the following Electron Configuration
Answer» ANSWER :2,8,8

Discussion

912.	The Bohr model of an atom is given below. Analyse it and find out the following Atomic number
Answer» ANSWER :18

Discussion

913.	The Bohr model of an atom is given below. Analyse it and find out the following The period and group of the element
Answer» ANSWER :PERIOD - 3 GROUP 18

Discussion

914.	The Bohr model of an atom is given below. Analyse it and find out the following The common name of the group.
Answer» ANSWER :NOBEL GASES

Discussion

915.	The best quality caoal with respect to percentage of carbon is "___________"
Answer» SOLUTION :ANTHRACITE

Discussion

916.	The BEC is formed by cooling a gas of extremely low density, about one hundred thousandth the density of normal air.
Answer» ANSWER :1

Discussion

917.	The basis of the classifications proposed by Dobereiner, Newlands and Mendeleev was……………….
Answer» ANSWER :ATOMIC MASSES

Discussion

918.	The average atomic mass of chlorine is 35.5 u.
Answer» ANSWER :TRUE

Discussion

919.	The average atomic mass of copper is 63.5. It exists as two isotopes which are ._(29)^(63)Cu and ._(29)^(65)Cu. Calculate the percentageof each isotope present in it.
Answer» Solution :LET the PERCENTAGEOF `overset(63)underset(29)Cu` isotope =x The percentage of `overset(65)underset(29)Cu` isotope =100-x From the above data the average atomic MASS of Cu=`(63xxx)/(100)+(65xx(10-x))/(100)` But the given average atomic mass of cu =63.5 `mu` `therefore (63x XX)/(100)+(65xx(100-x))/(100)=63.5` 63x+6500-65x=6350 -2x=6350-6500=-150 2x=150 x=75`mu` Percentage of `overset(63)underset(29)Cu` isotipe = 75% Percentage of `overset(65)underset(29)Cu`=25%

Discussion

920.	The average atomic mass of an element Y is 35.54. Find the percentages of isotopes ""_(17)^(37)Y and ""_(17)^(35)Y.
Answer» Solution :Let the percentage of `""_(17)^(35)`Y = x `therefore` Then the percentage of `""_(17)^(35) Y = 100 - x ` Average atomic MASS = `((37 xx x)+(35 xx (100 - x)))/(x + (100- x))` `therefore 35.5 = (37x + 3500 - 35x)/(100)` `therefore 3550 = 37x - 35x + 3500` `therefore` 50 = 2x THUS, the percentage of `""_(17)^(37)` Y = 25% the PERCENTAGES of `""_(17)^(35)` Y = 75 %

Discussion

921.	The average atimic mass of two isopoes with mass numbers A and A+2 is A+0.25. Calculate the percentage abundance of the isotopes.
Answer» Solution :(i) `(n_(1)xxA)+(n_(2)XX(A+2)=(n_1+n_2)(A+0.25)` from (ii) `87.5% and 12.5%`

Discussion

922.	The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes ""_(8)^(16)X and " "_(8)^(18) X in the sample?
Answer» Solution :Let the PERCENTAGE of`""_(8)^(16)` X be x Then the percentage of`""_(8)^(18)` X is (100-x ) `(16 xx (x)/(100)) + 18 xx ((100 - x)/(100)) = ` 16.2 `therefore (16x + 1800 - 18x )/(100) = 16.2` `therefore - 2x + 1800 = 16.2 xx 100` `therefore-2x + 1800 = 1620 ` `therefore - 2x = 1620 - 1800` `therefore -2x =- 180` `therefore x = 90` The percentage of ISOTOP `" "_(8)^(16)` X is 90 and the of `""_(8)^(18)`X is 10.

Discussion

923.	The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes ._(8)^(16)X and ._(8)^(18)X in the sample.
Answer» Solution :It is given that the average atomic mas of the sample of element X is 16.2. LET the PERCENTAGE of isotope `._(8)^(18)X` be Y%. THUS the percentage of isotope `._(8)^(16)X` will be `(100-Y)%` therefore `18xx(y)/(100)+16xx((100-y))/(100)=16.2` `(18y)/(100)+(16(100-y))/(100)=16.2` `(18y+1600-16y)/(100)=16.2` `18Y+1600-16Y=1620` `2Y+1600=1620` `2Y=1620-1600` `-Y=10` Therefore the percentage of isotope of `._(8)^(18)X` is 10 % And the percentage of isotope `._(8)^(16)X` is `(100-10)%=90%`.

Discussion

924.	The atoms of two element A and B contain thesame number of protons but different number of neutrons in their nuclei. What kind of element are A and B?
Answer» SOLUTION :A and B are ISOTOPES

Discussion

925.	The atomicity of K_(2)Cr_(2)O_(7) is ........
Answer» 9 11 10 12 Solution :11

Discussion

926.	The atomic radius of water is approximately …......... nanometer.
Answer» SOLUTION :`10^(-9)`

Discussion

927.	The atomic numbers of Ne, Mg. Al and P are 10, 12, 13 and 15. Out of Ne, Mg^(2+),Al^(3+) and P^(3-) , electronic structure of whichelement /ion differs?
Answer» <P>NE `MG^(2+)` `Al^(3+)` `p^(3-)` Solution :In Ne `Mg^(2+) and Al^(3+)` there are 10 electrons. So their electronic configuration is same. Whie is `P^(3-)` there are 18 electrons. HENCE its electronic configuration differs.

Discussion

928.	The atomic numbers of certain elements are given below. N=7, O=8, Cl=17 Identify the nature of covalent bonds In the molecules given below O_2
Answer» ANSWER :`O_2` - DOUBLE BOND

Discussion

929.	The atomic numbers of certain elements are given below. N=7, O=8, Cl=17 Identify the nature of covalent bonds In the molecules given below Cl_2
Answer» ANSWER :`Cl_2`-SINGLE BOND

Discussion

930.	The atomic number of two elements are given below.Mg = 12,O = 8 Which type of compound we be formed If these two elements combine together?
Answer» ANSWER :IONIC COMPOUND

Discussion

931.	The atomic numbers of certain elements are given below. N=7, O=8, Cl=17 Identify the nature of covalent bonds In the molecules given below N_2
Answer» ANSWER :`N_2` - TRIPPLE BOND

Discussion

932.	The atomic number of two elements are given below. Mg = 12, O = 8 Write the electron configuration of these elements.
Answer» ANSWER :Mg - 2, 8, 2 0 - 2, 6

Discussion

933.	The atomic number of sodium is 11. How many protons are there in the nucleus of sodium atom?How manu electrons does an atom of sodium contain ?How many electrons and protons does an ion of sodium which has a charge of +1 contain ?
Answer» SOLUTION :Protons =11, electrons 11, `Na^(+)` CONTAINS 10 electrons and 11 protons

Discussion

934.	The atomic number of elements x y and z are (a-z2),a and (a+2) repecitively y is a noble gas (not helium )them (a) prdict the group to whichx y and z belong (b) predict the formula of a molecule formed by x and z
Answer» Solution :(a) As y is a nobles GAS the group of y is 18th group or zero group X=A-2, group ofX is 16th groupor VI A Z=A+23,group of Y is 2nd group or IIA (B)X`rarr` valency =2 (ELECTRONEGATIVE) Z `rarr` valency =2 (elctropositive) Hence the formula is ZX

Discussion

935.	The atomic number of magnesium is 12 and Fluo¬rine is 9. Write the election configuration of these elements.
Answer» ANSWER :`12^(M-2,8,2)` `9^(F-2,7)`

Discussion

936.	The atomic number of element X is 8, while the atomic number of element Y is 4 . Hence. The valency of these elements is ...... .
Answer» 1 2 3 4 Answer :B

Discussion

937.	The atomic number of calcium is 20. It possesses K, L, M and N shells. Which shel(s) would be Alled incompletely ?
Answer» L, M, N M, N N K, L , M,N

Discussion

938.	The atomic number of calcium is 20. What is the number of electrons in its M-shell ?
Answer» SOLUTION :`{:(K,L,M,N),(2,8,8,2):}` `:.` ELECTRONS in M-shell=8

Discussion

939.	The atomic number of atom is 13. Its mass number is 27. Write the number of electron and neutrons in the atom.
Answer» ANSWER :NUMBER of ELECTRONS = 13 Number of NEUTRONS = `27-13=14`

Discussion

940.	The atomic number of atom is 13. Its mass number is 27. Write the electron configuration of this element.
Answer» ANSWER :2,8,3

Discussion

941.	The atomic number of an element that belongs to the IVA group and 4th period is __________
Answer» ANSWER :32

Discussion

942.	The atomic number of an element is 12. How many protons and electrons are there in an atom of the element ?
Answer» SOLUTION :NUMBER of protons = number of electrons =atomic number =12

Discussion

943.	The atomic number of an element is 12. What is its valency ?
Answer» SOLUTION :ATOMIC number = 12 `therefore` electronic CONFIGURATION = 2, 8, 2 `therefore` the valency is 2.

Discussion

944.	The atomic number of 4 elements A,B,C and D are 8,9,10 and 11 , respectively .The order of their atomic volume is
Answer» `AgtBgtCltD` `AltBltCgtD` `AgtBltCltD` `AltBgtCgtD` ANSWER :C

Discussion

945.	The atomic number and the mass number of an element M are 12 and 24 respectively . Calculate the number of neutrons in an atom of the element.
Answer» SOLUTION :NUMBER of NEUTRONS =MASS number-atomic number=24-12=12

Discussion

946.	The atomic masses are always whole numbers .
Answer» ANSWER :F

Discussion

947.	If the atomic mass of sodium is 23, the number of moles in 46gm of sodium is:
Answer» 1 2 `2.3` `4.6` ANSWER :B

Discussion

948.	Assertion : 1 amu is equal to 931.48 MeV. Reason: 1 amu is equal to 1/12th the mass of C^12 atom.
Answer» ANSWER :T

Discussion

949.	The atomic mass of sodiumis 23. The gram-atomic mass of sodium is ………….
Answer» ANSWER :23 G

Discussion

950.	The atomic mass of Sodium is 23. The number of moles in 46 g of Sodium is ___
Answer» ANSWER :2

Discussion

Explore topic-wise InterviewSolutions in .

The change of a solid directly into gas is called …….. .

The change of a liquid into vapour is called ……….

The change of a solid into gas is called …… .

The cation present in NH_(4)OH is

The cathode rays are produced when a gas at a very low pressure is subjected to an electric discharge .

The cathode of an electrochemical reaction involves …………………. .

The Catalyst used to decrease the rate of decomposition of hydrogen peroxide is ______

The bromination of acetylene gives __________ as the final product .

The boiling order of boiling points of diethyl ether, acetone and n-butyl alcohol are 35^(@)C, 56^(@)C and 118^(@)C , respectively. Which one is the following correctly represents their boiling points in kelvin scale ?

The boiling point of ethane is, - 88^(@)C.This temperature will be equivalent to :

The Bohr model of an atom is given below. Analyse it and find out the following Electron Configuration

The Bohr model of an atom is given below. Analyse it and find out the following Atomic number

The Bohr model of an atom is given below. Analyse it and find out the following The period and group of the element

The Bohr model of an atom is given below. Analyse it and find out the following The common name of the group.

The best quality caoal with respect to percentage of carbon is "___________"

The BEC is formed by cooling a gas of extremely low density, about one hundred thousandth the density of normal air.

The basis of the classifications proposed by Dobereiner, Newlands and Mendeleev was……………….

The average atomic mass of chlorine is 35.5 u.

The average atomic mass of copper is 63.5. It exists as two isotopes which are ._(29)^(63)Cu and ._(29)^(65)Cu. Calculate the percentageof each isotope present in it.

The average atomic mass of an element Y is 35.54. Find the percentages of isotopes ""_(17)^(37)Y and ""_(17)^(35)Y.

The average atimic mass of two isopoes with mass numbers A and A+2 is A+0.25. Calculate the percentage abundance of the isotopes.

The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes ""_(8)^(16)X and " "_(8)^(18) X in the sample?

The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes ._(8)^(16)X and ._(8)^(18)X in the sample.

The atoms of two element A and B contain thesame number of protons but different number of neutrons in their nuclei. What kind of element are A and B?

The atomicity of K_(2)Cr_(2)O_(7) is ........

The atomic radius of water is approximately …......... nanometer.

The atomic numbers of Ne, Mg. Al and P are 10, 12, 13 and 15. Out of Ne, Mg^(2+),Al^(3+) and P^(3-) , electronic structure of whichelement /ion differs?

The atomic numbers of certain elements are given below. N=7, O=8, Cl=17 Identify the nature of covalent bonds In the molecules given below O_2

The atomic numbers of certain elements are given below. N=7, O=8, Cl=17 Identify the nature of covalent bonds In the molecules given below Cl_2

The atomic number of two elements are given below.Mg = 12,O = 8 Which type of compound we be formed If these two elements combine together?

The atomic numbers of certain elements are given below. N=7, O=8, Cl=17 Identify the nature of covalent bonds In the molecules given below N_2

The atomic number of two elements are given below. Mg = 12, O = 8 Write the electron configuration of these elements.

The atomic number of sodium is 11. How many protons are there in the nucleus of sodium atom?How manu electrons does an atom of sodium contain ?How many electrons and protons does an ion of sodium which has a charge of +1 contain ?

The atomic number of elements x y and z are (a-z2),a and (a+2) repecitively y is a noble gas (not helium )them (a) prdict the group to whichx y and z belong (b) predict the formula of a molecule formed by x and z

The atomic number of magnesium is 12 and Fluo¬rine is 9. Write the election configuration of these elements.

The atomic number of element X is 8, while the atomic number of element Y is 4 . Hence. The valency of these elements is ...... .

The atomic number of calcium is 20. It possesses K, L, M and N shells. Which shel(s) would be Alled incompletely ?

The atomic number of calcium is 20. What is the number of electrons in its M-shell ?

The atomic number of atom is 13. Its mass number is 27. Write the number of electron and neutrons in the atom.

The atomic number of atom is 13. Its mass number is 27. Write the electron configuration of this element.

The atomic number of an element that belongs to the IVA group and 4th period is __________

The atomic number of an element is 12. How many protons and electrons are there in an atom of the element ?

The atomic number of an element is 12. What is its valency ?

The atomic number of 4 elements A,B,C and D are 8,9,10 and 11 , respectively .The order of their atomic volume is

The atomic number and the mass number of an element M are 12 and 24 respectively . Calculate the number of neutrons in an atom of the element.

The atomic masses are always whole numbers .

If the atomic mass of sodium is 23, the number of moles in 46gm of sodium is:

Assertion : 1 amu is equal to 931.48 MeV. Reason: 1 amu is equal to 1/12th the mass of C^12 atom.

The atomic mass of sodiumis 23. The gram-atomic mass of sodium is ………….

The atomic mass of Sodium is 23. The number of moles in 46 g of Sodium is ___