Archives

In photosynthesis, 6 molecules of carbon dioxide combine with an equal number of water molecules through a complex series of reactions to give a molecule of glucose having a molecular formula C6H12O6. How many grams of water would be required to produce 18 g of glucose? Compute the volume of water so consumed assuming the density of water to be 1 g cm^-3

Answer: 1 mole of glucose needs 6 moles of water 180 g of glucose needs (6 × 18) g of water 1 g of glucose will need 108/ 180 g of water.... View Article

Write the formulae for the following and calculate the molecular mass for each one of them. (a) Caustic potash (b) Baking powder (c) Limestone (d) Caustic soda (e) Ethanol (f) Common salt

Answer: The formulae for the following and calculate the molecular mass for each one of them. Ser. No. Compound Formula Molecular mass A... View Article

Fill in the blanks : Formula of sodium carbonate is…………………….. and that of ammonium sulphate is………………….

Answer: Formula of sodium carbonate is Na2CO3and that of ammonium sulphate is (NH4)2SO4 Sodium carbonate is an inorganic chemical compound, it... View Article

Fill in the blanks: The formula unit mass of Ca₃ (PO₄)₂ is………………….

Answer: The formula unit mass of Ca3(PO4)2 is 310 Formula unit mass is defined as the sum of the mass of all the atoms each multiplied by its... View Article

Fill in the blanks : A group of atoms carrying a fixed charge on them is called…………………

Answer: A group of atoms carrying a fixed charge on them is called Polyatomic ions. Polyatomic ions are ions that contain more than one atom.... View Article

Fill in the blanks : In a chemical reaction, the sum of the masses of the reactants and products remains unchanged. This is called …………………

Answer: In a chemical reaction, the sum of the masses of the reactants and products remains unchanged. This is called Law of conservation of... View Article

A sample of ethane (C₂H₆) gas has the same mass as 1.5 ×10²⁰ molecules of methane (CH₄). How many C₂H₆ molecules does the sample of gas contain?

Answer: 1 mole = 6.02 x 1023 molecules of methane 1.5 x 1020 molecules of methane is = (1.5 x 1020 x 1) ÷ (6.02 x 1023) moles 1.5 x 1020... View Article

A silver ornament of mass ‘m’ gram is polished with gold equivalent to 1% of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament.

Answer: 1 : 182.41 Mass of silver = m g Mass of gold = m /100g Number of atoms of silver = (m /108) × NA Number of atoms of gold = m /... View Article

Compute the difference in masses of one mole each of aluminium atoms and one mole of its ions. (Mass of an electron is 9.1×10^-28 g). Which one is heavier?

Answer: Let us calculate the mass of one mole of aluminium atom Al - 3e- → Al+3(3 moles of electrons) Mass of three moles of electrons = (3... View Article

What are ionic and molecular compounds? Give examples.

Answer: Ionic compounds can be defined as crystalline solids formed by neatly packed ions of opposite charge. Ionic compounds are usually... View Article

A gold sample of gold and the rest copper. Hoe many atoms of gold are present in one gram of this sample of gold ?

Answer: 2.77 × 1021 atoms One gram of gold sample will contain 90/100 = 0.9g of gold Number of moles of gold = mass of gold / atomic mass... View Article

Compute the number of ions present in 5.85 g of sodium chloride.

Answer: 1.2042 ×1023 ions The molar mass of NaCl = The atomic weight of sodium(Na) + The atomic weight of Chlorine(Cl) The atomic weight... View Article

Which has more number of atoms? 100g of N₂ or 100 g of NH₃

Answer: The number of moles can be calculated using the formula, No.of moles = Weight of the substance/Molecular weight of the substance 100... View Article

Compute the difference in masses of 10³ moles each of magnesium atoms and magnesium ions. (Mass of an electron = 9.1×10^-31 kg)

Answer: 1.096 × 10–3kg Mg atom has 12 electrons Mg2+ has 10 electrons Mg2+ ion and Mg atom differ by two electrons. 103 moles of... View Article

Express each of the following in kilograms (a) 5.84×10^-3 mg (b) 58.34 g (c) 0.584g (d) 5.873×10^-21g

Answer: A kilogram (symbol: kg) is the base unit of mass in the International System of Units (SI). 1 Kilogram is equal to 1000 Grams. 1 kg =... View Article

What is the SI prefix for each of the following multiples and submultiples of a unit? (a) 10³ (b) 10^-1 (c) 10^-2 (d) 10^-6 (e) 10^-9 (f) 10^-12

Answer: (a) 103 = 1000 = kilo (b) 10–1 = 1/10 = 0.1= deci (c) 10–2 = 1/100 = 0.01= centi (d) 10–6 = 0.000 001 = micro (e)... View Article

The visible universe is estimated to contain 10²² stars. How many moles are present in the visible universe ?

Answer: 0.0166 moles 1 mole = 6.022 × 1023 The number of moles (n) = Given number of particles(N)/Avogadro number(NA) n = 1022/6.022... View Article

Fill in the missing data in the Table 3.1

Species property H2O CO2 Na atom MgCl2 No of Moles 2 – – 0.5 No of particles – 3.011×1023 – 0 Mass 36g... View Article

Raunak took 5 moles of carbon atoms in a container and Krish also took 5 moles of sodium atoms in another container of same weight. (a) Whose container is heavier? (b) Whose container has more number of atoms?

Answer: Atomic weight of sodium (Na) = 23 Mass of sodium atoms carried by Krish = 5 ×23 g ∴ Mass of sodium atoms carried by Krish... View Article

A sample of Vitamin C is known to contain 2.58 ×10²⁴ oxygen atoms. How many moles of oxygen atoms are present in the sample?

Answer: 4.28 mol One mole of a substance is equal to the substance’s 6,022 x 1023 units. The 6.022 x 1023 number is known as the number of... View Article

M	T	W	T	F	S	S
		1	2	3	4	5
6	7	8	9	10	11	12
13	14	15	16	17	18	19
20	21	22	23	24	25	26
27	28	29	30