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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
Name a non-metal which is tetratomic. |
| Answer» The non-metal is phosphorus. It exists as P molecule and is tetratomic. | |
| 102. |
The formula of the sulphate of an element X is `X_(2)(SO_(4))_(3)`. The formula of nitride of element X will be :A. 3B. `XN_(2)`C. `XN`D. `X_(2)N_(3)` |
| Answer» Correct Answer - C | |
| 103. |
Convert 12 g of oxygen gas into moles. |
| Answer» Correct Answer - `0.375` mol | |
| 104. |
What name is the mass of `0.2` mole of oxygen atoms ? |
| Answer» Correct Answer - 3.2 g | |
| 105. |
How many moles are `3.6 g` of water ? |
| Answer» Correct Answer - 0.2 mol | |
| 106. |
Write the molecular formulae of all the compounds that can be formed by the combination of the following ions: `Cu^(2+), Na^(+), Fe^(3+), C^(-),SO_(4)^(2-)`. |
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Answer» In this case, the compounds can be formed by the combination of cations and anions. Therefore, the molecule. formulae of different compounds are: `CuCl_(2), CuSO_(4), NaCl, Na_(20SO_(4)), FeCl_(3), Fe((SO)_(4))_(3)`. |
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| 107. |
Write the formulae and the names of the ions formed by the combination of (i)`Fe^(3+) and SO_(4)^(2-)` (ii)`NH_(4)^(+) and CO_(3)^(2-)` |
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Answer» `Fe_(2)(SO_(4))_(3)`: Ferric sulphate or Fe (III) sulphate. (ii)`(NH_(4))_(2)CO_(3)`:Ammonium carbonate or Ammonium(I)carbonate. |
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| 108. |
Give the names of the elements present in the following compounds: (a) Quickline (B) Hydrogen bromide (c ) Baking soda (D) Potassium sulphate |
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Answer» The names of elements present can be given only if the chemical formula of the compound is know For example, (a)Quick lime: It is the commercial name of the compound. Its chemical name is calcium oxide and the chemical formula is CaO. (b)Hydrogen bromide:The chemical formula of the compound is HBr. Elements present:hydrogen(H),bromide(Br). (c )Baking powder:It is the commercial name of the compound. Its chemical name is sodium hydrogen carbonate and the chemical formual is `NaHCO_(3)`. Elements present:sodium (Na),hydrogen (H), carbon(C ),oxygen(O). (d)Potassium sulphate:The chemical formula of the compound is `K_(2)SO_(4)` Elements present:potassium (K), sulphur(S),oxygen(O). |
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| 109. |
Write the chemical formulae for the following compounds that can be formed by the combination of followin ions: `Cu^(2+),Na^(+),Fe^(3+),Cl^(-),SO_(4)^(2-),PO_(4)^(3-)` |
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Answer» `"For" Cu^(2+)"ion", CuCl_(2), CuSO_(4), Cu_(3)(PO_(4))_(2)` `"For" Na^(2+)"ion", NaCl, Na_(2)SO_(4), Na_(3)PO_(4)` `"For" Fe^(3+)"um", FeCl_(3), Fe_(2)(SO_(4)),FePO_(4)` |
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| 110. |
Write the formula and names of the compounds formed by the followin ions. (a)Potassium ion and iodide ion. (b)Sodium ion and sulphide ion. (c )Aluminium ion and phosphate ion. |
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Answer» The compound are: `(a)underset("Potassium iodide")(Kl)` (b)`underset("Sodium sulphide")(Na_(2)S)` (c)`underset("Aluminium phosphate")(AlPO_(4))` |
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| 111. |
Write the chemical formual the followin compounds and also calcuate their formula write mass (a) Baking soda (b) Caustic soda (c )Common salt (d) Magnessium (e )Sodium carbonate. |
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Answer» Baking soda `(NaHCO_(3))` `"Formula units mass"="Atomic mass of Na"+"Atomic mass of H"+"Atomic mass of C"+3xx"Atomic mass of O"` (b) Caustic soda `"Formula unit mass"="Atomic mass of Na"+"Atomic mass of O"+"Atomic mass of H"=23+16+1=40u` (c )Common salt (NaCl) `"Formulae unit mass"="Atomic mass of Na"+Aromic mass of Cl"=23+35.5=58.5u` (d) Magnesium sulphate `(MgSO_(4))` `"Formulae unit mass"="Atomic mass of Mg"+"Aromic mass of S"+4xx"atomic mass of O"=24+32+4xx"atomic mass"` `=24+32+4xx16=120u` (e )Sodium carbonate `(Na_(2)CO_(3))` `"Formulae unit mass"=2xx"Atomic mass of Na"+"Aromic mass of C"+3xx"atomic mass of O"=24+32+4xx"atomic mass of O"` `=2xx23+12+3xx16=106u` |
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| 112. |
What weight of oxygen gas will contain the same number of molecules as `56` g of nitrogen gas ? `(O = 16 u , N = 14 u )` |
| Answer» Correct Answer - D | |
| 113. |
Calculate the number of molecules in `4 g` of oxygen . |
| Answer» Correct Answer - `7.528 xx 10^(22)` molecules | |
| 114. |
Convert into moles: (i)20g of water (ii)20g of carbon dioxide |
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Answer» Gram molar mass of water `(H_(2)O)=(2xx1+16)=18g` 18g of watwer represent moles =1mol 20g of water represent moles `=((20g))/((18g))xx(1"mol")=1.11"mol"` (ii) Gram molar mass of carbon dioxide `(CO_(2))=(12+2xx16)=44g` 44g of carbon dioxide represent moles =1mol 20g of carbon dioxide represent moles=`=((20g))/((44g))xx(1"mol")=0.45"mol"` |
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| 115. |
Convert `12.044 xx 10^(22)` molecules of sulphur dioxide into moles. |
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Answer» We know that : `6.022 xx 10^(23)` molecules of sulphur dioxide ` = 1` mole So, `12.044 xx 10^(22)` molecules of sulphur dioxide `= (1)/(6.022 xx 10^(23)) xx 12.044 xx 10^(22)` `= 2/10` `0.2` mole Thus, `12.044 xx 10^(23)` molecules of sulphur dioxide are `0.2` mole. |
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| 116. |
Convert into mole. (a) 12 g of oxygen gas (b) 20 g of water (c) 22 g of carbon dioxide. |
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Answer» Correct Answer - (a) 0.375 mole (b) 1.11 mole (c ) 0.5 mole (a) 32 g of oxygen gas = 1 mole Then, 12g of oxygen gas = 12/32 mole = 0.375 mole (b) 18g of water = 1 mole Then, 20 g of water = 20/18 mole = 1.11 moles (c) 44g of carbon dioxide = 1 mole Then, 22g of carbon dioxide = 22/44 mole = 0.5 mole |
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| 117. |
Fill in the blanks. a) In a chemical reaction, the sum of the masses of the reactants and products remains unchanged. This is called law of conservation of mass. b) A groupof atoms carrying a fixed charge on them is called polyatomic ion. The formula unit masss of `Ca_(3)(PO_(4))_(2)` is 310g. d) Formula of sodium carbonate is .............. and that of ammonium sulphate is............. |
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Answer» (a)Law of conservation of mass (b)Polyatomic ions (c )`3xx"Atomic mass of Ca"+2xx"Atomic mass of P"+8xx"Atomic mass of O"` `=3xx40+2xx31+8xx16=120+62+128=310u` (d)`Na_(2)CO_(3), (NH_(4))_(2)SO_(4)` |
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| 118. |
Convert into moles : (a) 12 g of oxygen gas (b) 20 g of water (c ) 22 g of carbon dioxide (Atomic masses : `O = 16 u, H = 1 u` and `C = 12 u`) |
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Answer» (a) Oxygen gas consists of `O_(2)` molecules . So, molecular mass of oxygen gas `(O_(2)) = 16 xx 2 = 32 u` Now, 1 mole of oxygen gas = Molecular mass of ox ygen in grams `= 32 g` If 32 g of oxygen gas `= 1` mole Then 12 g of oxygen gas `= 1/32 xx 12` mole `= 0.375` mole (b) Water consists of `H_(2)O` molecular mass of water `(H_(2)O) = 1 xx 2 + 16 = 18 u`. Now, 1 mole of water = Molecular mass of water in grams ` = 18 g` If 18 g of water `= 1` mole Then 20 g of water = `1/18 xx 20` mole `= 1.11` mole (c ) Carbon dioxide consists of `CO_(2)` molecules. So, molecular mass of carbon dioxide `(CO_(2)) = 12 + 1 xx 2` ` = 12 + 32 = 44 u`. Now, 1 mole of carbon dioxide = Molecular mass of carbon dioxide in grams `= 44 g` If 44 g of carbon dioxide = 1 mole Then, 22 g of carbon dioxide `= 1/44 xx 22` mole `= 1/2` mole `= 0.5` mole |
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| 119. |
Calculate the molecular mass of the following substance (i) water `(H_(2)O)` (ii) Sulphur dioxide `(SO_(2))` (iii) Oxygen molecule `(O_(2))` (iv) Carbon monoxide (CO) |
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Answer» (i)Water `(H_(2)O)` `"Molecular mass of "H_(2)O=(2xx"Atomic mass of H")+1xx"Aromic mass of O")` (ii) Sulphur dioxide `(SO_(2))` `"Molecular mass of "S_(2)O=(1xx"Atomic mass of S")+(2xx"Aromic mass of O")` `=(1xx32u)+(2xx16u)=64u` (iii) Oxygen molecule `(O_(2))` `"Molecular mass of "O_(2)=2xx"Aromic mass of O"` =`(2xx16u)=32u` (iv) Carbon monoxide (CO) `"Molecular mass of "CO=(1xx"Aromic mass of C")+(1xx"Atomic mass of O")` =`(1xx12u)+(1xx16u)=28u` |
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| 120. |
Convert 22 g of carbon dioxide `(CO_(2))` into moles. (Atomic masses : `C = 12 u, O = 16 u`) |
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Answer» Here we have been given that the atomic mass of carbon `(C )` is `12 u` and the atomic mass of oxygen (O) is `16 u`. So, first of all we will calculate the mass of 1 mole of carbon dioxide by using these values of atomic masses. The mass of 1 mole of carbon dioxide `(CO_(2))` will be equal to its molecular mass expressed in grams. That is : `1` mole of `CO_(2)` = Molecular mass of `CO_(2)` in grams `=` Mass of C + Mass of `O xx 2` `= 12 + 16 xx 2` `= 44` grams So, the mass of 1 mole of carbon dioxide is `44` grams. Now, 44 g of carbon dioxide `= 1` mole So, 22g of carbon dioxide `= 1/44 xx 22` mole `= 1/22` `= 0.5` mole , (or `0.5` mol) Thus, 22 grams of carbon dioxide are equal to `0.5` mole. |
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| 121. |
Write the chemical symbols and Latin names of (i) gold (ii) mercury? |
| Answer» (i) Au (Aurum) (ii) Hg (Hydrargyrum). | |
| 122. |
Potassium chlorate decomposes, on heating, to form potassium chloride and oxygen. When 24.5 g of potassium chlorate is decomposed completely, then `14.9g` of potassium chloride is formed. Calculate the mass of hydrogen formed. Which law of chemical combination have you used in solving this problem ? |
| Answer» Correct Answer - `9.6 g` ; Law of conservation of mass | |
| 123. |
The symbol of a metal element which is used in making thermometers is :A. AgB. HgC. MgD. Sg |
| Answer» Correct Answer - B | |
| 124. |
If 12 gram of carbon has x atoms, then the number of atoms in 12 grams of magnesium will be :A. xB. 2xC. `x/2`D. `1.5 x` |
| Answer» Correct Answer - Chlorine ion, `Cl^(-)` | |
| 125. |
Calculate the mass in grams of `0.17` mole of hydrogen sulphide , `H_(2)S`. (Atomic masses : ` H = 1 u, S = 32 u`) |
| Answer» Correct Answer - `5.78 g` | |
| 126. |
How many grams of neon will have the same number of atoms as 4 grams of calcium ? (Atomic masses : `Ne = 20 u, Ca = 40 u`) |
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Answer» To solve such problems we should remember that "equal number of moles of all the elements contain equal number of atoms". (i) Let us first convert 4 grams of calcium into moles. We have been given that the atomic mass of calcium is 40 u, so 1 mole of calcium is `40` grams. Now, `40 g` of calcium `= 1` mole So, `4 g` of calcium `= 1/40 xx 4` mole `= 1/10` mole Now, `1/10` mole of calcium will have the same number of atoms as `1/10` mole of neon. So, we should now convert `1/10` mole of neon into mass in grams. (ii) The atomic mass of n eon is `20u`, so 1 mole of neon will be equal to 20 grams. Now, `1` mole of neon `= 20 g`, So, `1/10` mole of neon `= 20 xx 1/10` g `= 2 g` Thus, 2 grams of neon will contain the same number of atoms as 4 grams of calcium. |
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| 127. |
Which contains more molecules, 10 g of sulphur dioxide `(SO_(2))` or `10 g` of oxygen `(O_(2))` ? (Atomic masses : `S = 32 u , O = 16 u`) |
| Answer» Correct Answer - A | |
| 128. |
The English name of an element is potassium, its Latin name will be :A. plumbumB. cuprumC. kaliumD. natrium |
| Answer» Correct Answer - C | |
| 129. |
The law of conservation of mass was given by :A. DaltonB. ProustC. LavoisierD. Berzelius |
| Answer» Correct Answer - C | |
| 130. |
In a chemical reaction, 10.6g of sodium carbonate reacted with 12g of ethanoic acid. The products obtained were 4.4g of carbon dioxide, 16.4 of sodium ethanoate and 1.8g of water. (a)Write a word equation, clearly showing the reactants and products as given above. (b)Also show that this data is in aggrement with the law of conservations of mass. |
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Answer» (a)The word equation for the chemical reaction is `underset("reactants")("Sodium carbonate")+underset("reactants")("Ethanoic acid") to underset("products")("Sodium ethanoate")+underset("produts")("Carbon dioxide")+underset("products")"Water"` Mass of reactants=(10.6+12)=22.6g Mass of products=(16.4+4.4+1.8)=22.6g Since the mass of reactants species is equal to the mass of the product species. the data illustrates the law of conservation of mass. |
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| 131. |
How many grams of magnesium will have the same number of atoms as 6 grams of carbon ? `(Mg = 24 u , C = 12 u )` |
| Answer» Correct Answer - A::B | |
| 132. |
If 1 g of sodium carbon contains x atoms, what will be the number of atoms in 1 g of magnesium ? `(C= 12u, Mg = 24 u)` |
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Answer» The ratio of atoms in carbon and magnesium will be same as the ratio of their moles. So, first of all we should find out: (i) moles of carbon in 1 gram of carbon, and (ii) moles of magnesium in 1 grams of magnesium This can be done as follows. (a) 1 mole of carbon = Gram atomic mass of carbon `= 12` grams Now, 12g of carbon `= 1` mole So, `1 g` of carbon `= 1/12` mole Thus, we have `1/12` mole of carbon element and it contains x atoms of carbon. Now, since an equal number of moles of all moles of all the elements contains an equal number of atoms, so `1/12` moles of magnesium will also contain x atom s of magnesium. We will now calculate the moles of magnesium in 1 grams of magnesium. (b) 1 mole of magnesium = Grams atomic mass of magnesium `= 24` grams Now, `24 g` of magnesium = 1 mole So, 1g of magnesium `= 1/24` mole We know that : `1/12` mole of magnesium contains `= x` atoms So, `1/24` mole of magnesium contains `= (x xx 12)/(24)` atoms `= x/2` atoms Thus, if 1 gram of carbon contains x atoms, then 1 gram of magnesium will have `x/2` atoms in it. |
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| 133. |
If one grams of sulphur contains x atoms, calculate the number of atoms in one gram of oxygen element. (Atomic masses : `S = 32 u , O = 16 u`) |
| Answer» Correct Answer - B | |
| 134. |
Calcualte the number of moles of magnesium present in a magnesium ribbon weighting 12g. Molar atomic mass of magnesium is 24 g `mol^(-1)`. |
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Answer» Mass of magnesium (Mg)=12g Molar mass of magnesium(Mg)=`24gmol^(-1)` `"No. of moles of magnesium(Mg)"=(("Mass"))/(("Molar aromic mass"))=((12g))/((24gmol^(-1)))=0.5"mol"` |
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| 135. |
Fill in the following blanks : (a) 1 mole contains `"…………."` atoms, molecules or ions of a substance. (b) A mole represents an `"…………."` number of particles of a substances. (c ) 60 g of carbon element are `"…………."` moles of carbon atoms. (d) 0.5 mole of calcium element has a mass of `"…………."`. (e) 64 g of oxygen gas contains `"…………."` moles of oxygen atoms. |
| Answer» Correct Answer - (a) `6.022 xx 10^(23)` , (b) Avogadro , (c ) 5 , (d) 20 g , (e ) 4 | |
| 136. |
(a) How many atoms are there in exactly 12g of carbon-12 element ? `(C = 12 u)` (b) What name is given to this number ? (c ) What name is given to the amount of substance containing this number of atoms ? |
| Answer» Correct Answer - (a) `6.022 xx 10^(23)` , (b) Avogadro , (c ) Mole | |
| 137. |
Calculate the molecular masses of the following compounds : (a) Methane, `CH_(4)` , (b) Ethane, `C_(2)H_(6)`, (c ) Ethane, `C_(2)H_(4)` , (d) Ethyne, `C_(2)H_(2)` (Atomic masses: `C = 12 u , H = 1 u`) |
| Answer» Correct Answer - (a) 16 u , (b) 30 u , (c ) 28 u , (d) 26 u | |
| 138. |
Out of ozone, phosphorus , sulphur and krypton, them elements having the lowest and highest atomicities are respectively:A. sulphur and kryptonB. krypton and ozoneC. phosphorus and sulphurD. krypton and sulphur |
| Answer» Correct Answer - D | |
| 139. |
The atomicites of ozone, sulphur, phosphorus and organ are respectively :A. 8,3,4 and 1B. 1,3,4 and 8C. 4,1,8 and 3D. 3,8,4 and 1 |
| Answer» Correct Answer - D | |
| 140. |
Calculate the molar mass of the following substances. (a) Ethyne, `C_(2)H_(2)` (b) Sulphur molecule, `S_(8)` (c) Phosphorus molecule, `P_(4)` (Atomic mass of phosphorus = 31) (d) Hydrochloric acid, HCl (e) Nitric acid, `HNO_(3)` |
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Answer» (A) Ethyne, `C_(2)H_(2)` Molar mass of `C_(2)H_(2)`=`=(2xx"Aromic mass of C")+(2xx"Atomic mass of H")` `=(2xx12u)+(2xx1u)=26u` (b) Sulphur molecule, `S_(B)` `"Molar mass of "S_(B)=8xx"Atomic mass of S"=(8xx32u)=256u` (c )Phosphorus molecule, `P_(4)` `"Molar mass of "P_(4)=4xx"Atomic mass of P"=(4xx31u)=124u` (d) Nitric acid, `HNO_(3)` `"Molar mass of "HNO_(3)=(1xx"Atomic mass of H")+(1xx"Atomic mass of N")+(3xx"Atomic mass of O")` `=(1xx1u)+(1xx35.5u)=36.5u` |
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| 141. |
What is the mass of— (a) 1 mole of nitrogen atoms? (b) 4 moles of aluminium atoms (Atomic mass of aluminium = 27)? (c) 10 moles of sodium sulphite `(Na_(2)SO_(3))`? |
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Answer» (a) 1 mole of nitrogen (Al) atoms=27u Mass of 1 mole of nitrogen (Al) atoms=14u (b) 4 moles of aluminium atoms Mass of 1 mole of aluminimum (Al) atoms=27u Mass of 4 moles of aluminimum (Al) atoms=`4xx27=108u` (c )10moles of sodium sulphide `(Na_(2)SO_(3))` `"Mass of "Na_(2)SO_(3)=2xx"Atomic mass of Na"+"Atomic mass of S"+3xx"Atomic mass of O"` `=2xx23+32+3xx16=126u` 1 mole of sodium sulphide has mass =126u 10 moles of sodium sulphide have mass `=10xx126=1260u` |
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| 142. |
Why is a cation so named? |
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Answer» When electric current is passed through the solution of a salt like sodium chloride (NaCl), the positive ion .`(Na^(+))` migrates towards cathode (negative electrode). It is therefore, called cation. Please remember that .Positive ion migrating towards cathode on passing electric current is known as cation. Negative ion migrating towards anode on passing electric current is known as anion. |
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| 143. |
What happens to an element A if its atom gains two electrons? |
| Answer» It changes to a divalent anion `(A^(2-))` | |
| 144. |
An element X has valency 3 while the element Y has valency 2. Write the formula of the compound berween X and Y |
| Answer» The formula of the compound between X and Y is `X_(2)Y_(3)`. | |
| 145. |
Formula of the carbonate of a metal M is `M_(2)CO_(3)`. Write the fomula of its chloride. |
| Answer» The valency of the metal (M) in `M_(2)CO_(3), "is" (1+)`i.e. metal exists as `M^(+)` ion. Therefore, the formula of metal chloride is MCl. | |
| 146. |
Calculate the molecular mass of ethanoic acid, `CH_(3)COOH`. (Atomic masses : `C = 12 u , H = 1 u , O = 16 u`) |
| Answer» Correct Answer - 60 u | |
| 147. |
The atoms of which of the following pair of elements are most likely to exist in free state ?A. hydrogen and heliumB. argon and carbonC. neon and nitrogenD. Helium and neon |
| Answer» Correct Answer - B | |
| 148. |
If 32 g of sulphur has x atoms, then the number of atoms in 32 g of oxygen will be :A. `x/2`B. `2x`C. `x`D. `4x` |
| Answer» Correct Answer - b | |
| 149. |
(a)Define atomic mass unit. How is it linked with relative atomic mass? (b) How do you know the presence of atoms if they do not exist independently for most of the elements? |
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Answer» Atomic mass unit (u) is 1/12 of the mass of one atom o of C-12. Relative atomic mass of the atom of an element is the average mass of the atoms as compared to 1//12th of the mass of C-12 atom `"Relative atomic mass of an element"=("Average mass of 1 atom of the element")/("1/12th of mass of 1 atom of C-12")` (b)Atoms of most of the elements do not exist independently. However, they combine in specific number to form molecules or ions which we can feel and know about their presence. For example. A molecules of `H_(2)SO_(4)`, consists of 2 atoms of H+1 atom of S+4 atoms of O A molecules of `C_(12)H_(22)O_(11)` consists of 12 atoms of C+22 atoms of H+11 atoms of O. Ammonium ion `(NH_(4)^(+))` consists of 1 atom of N+4 atoms of H. |
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| 150. |
What do you understand from the statement "relative atomic mass of sulphur is `32^(@)`? |
| Answer» This means that an atom of sulphur is 32 times heavier as compared to 1/12 of the mass of 1 atom of C-12(1u) | |