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What is the difference between sodium atom and sodium ion?
|
|
0
|
2774
|
November 24, 2016
|
|
How do molecules exist in a chemical reaction?
|
|
0
|
2034
|
November 24, 2016
|
|
What is the relative atomic mass of an element?
|
|
1
|
770
|
November 24, 2016
|
|
Define atomic mass unit. State how do atoms exist?
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|
0
|
7748
|
November 24, 2016
|
|
Mention any two important rules for writing a chemical formula
|
|
1
|
2872
|
November 24, 2016
|
|
What change would you observe in the overall mass of the content?
|
|
1
|
896
|
November 24, 2016
|
|
Write the Latin names of sodium and iron
|
|
0
|
1757
|
November 24, 2016
|
|
Define Avogadro's constant. How is it related to mole?
|
|
0
|
3942
|
June 29, 2016
|
|
What is the difference between cation and an anion?
|
|
0
|
2967
|
June 29, 2016
|
|
(i) Name the body which approves the nomenclature of elements and compounds. (ii) The symbol of sodium is written as Na and not as S. Give reason. (iii) Name one element which forms diatomic and one which forms tetraatomic molecules
|
|
0
|
3718
|
June 29, 2016
|
|
(a) Define atomicity. (b) Give an example for an element which is monoatomic and a polyatomic molecule
|
|
0
|
2169
|
June 29, 2016
|
|
Mention the two postulates of Dalton’s Atomic Theory that explain: (a) Law of Conservation of Mass (b) Law of Constant Proportions
|
|
0
|
3183
|
June 29, 2016
|
|
(a) What is the law of constant proportions ? Explain with the help of an example. (b) Which postulate of Dalton's atomic theory is in agreement with this law?
|
|
0
|
1338
|
June 29, 2016
|
|
Calculate the number of moles in 5.75 g of sodium (atomic mass of sodium - 23)
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|
0
|
4250
|
June 29, 2016
|
|
(a) What are polyatomic ions ? (b) Write the formulae and names of the compounds formed by combination of:
|
|
0
|
1241
|
June 30, 2016
|
|
Which amongst the following has more number of atoms, 11.5 g of sodium or 15 g of calcium ? How?
|
|
0
|
7433
|
June 30, 2016
|
|
What is the mass of one mole of oxygen atoms ? Convert 12 g of oxygen gas into mole
|
|
0
|
1378
|
June 30, 2016
|
|
What is the difference between an atom and a molecule?
|
|
0
|
658
|
June 30, 2016
|
|
(a) Write chemical formulae of sodium sulphate. (b) Name one element each which forms diatomic and tetraatomic molecule
|
|
0
|
817
|
June 30, 2016
|
|
State thepostulate of Dalton's atomic theory which led to the law of conservation of mass. Calculate the molecular mass of water
|
|
0
|
728
|
June 30, 2016
|
|
Differentiate between: (i) Atom and molecule. (ii) Molecular mass and formula unit mass
|
|
0
|
623
|
June 30, 2016
|
|
Calculate the number of particles in each of the following: (a) 48 g of Mg (b) 8 g of O2 (c) 0.1 mole of carbon (Atomic mass Mg = 24 u, O = 16 u, C = 12 u, Avogadro constant (NA = 6.022 x 10^23)
|
|
0
|
9818
|
June 30, 2016
|
|
Calculate the following quantities in 5.6 g of nitrogen (Atomic mass of N =14u) : (a) Number of moles of N2. (b) Number of molecules of N2. (c) Number of atoms of nitrogen
|
|
0
|
8795
|
June 30, 2016
|
|
(a) Define molar mass. What are its units ? (b) Write the names of compounds represented by the following formulas : (i) K2C03 (ii) Na2SO4 (iii) Ca(HCO3)2 (iv) H2SO4
|
|
0
|
1092
|
June 30, 2016
|
|
A gas jar contains 1.7 g of ammonia gas. Calculate the following: (i) Molar mass of ammonia. (ii) How many moles of ammonia are present in the gas jar ? (iii) How many molecules of ammonia are present in the sample?
|
|
0
|
10759
|
June 30, 2016
|
|
Calculate number of atoms in 120 g of calcium and 120 g of iron. Which one has more number of atoms and how much is the difference ? (Given atomic mass of calcium - 40 u and iron = 56 u)
|
|
0
|
10840
|
June 30, 2016
|
|
(a) Calculate the mass of 0.5 mole of oxygen atoms. (b) Calculate the number of molecules of glucose present in its 90 grams (molecular mass of glucose is 180 u) (c) Calculate number of moles of water in 2 grams of water. Atomic mass of H = 1 u, O = 16 u
|
|
0
|
13938
|
June 30, 2016
|
|
With a labelled diagram describe an actimty to demonstrate "the law of conservation of mass."
|
|
0
|
15192
|
June 30, 2016
|
|
The ratio of hydrogen and oxygen in water is 1:8 by mass, find out their ratioby number ofatoms, in one molecule of water. (Atomic mass :H=1 u, 0=16u) (b) Write the formulae of the following compounds : (i) Ammonium sulphate (ii) Magnesium chloride
|
|
0
|
4043
|
June 30, 2016
|
|
The chemical formula of chloride of metal 'M' is MCI. Write the chemical formula of its chloride, bicarbonate and sulphide
|
|
0
|
1878
|
June 30, 2016
|