A significant figure is defined as -

How many moles of lead (II) chloride will be formed from a reaction between 6.5g of PbO and 3.2g of HCl?

The concentrated nitric acid is 70% HNO₃. The amount of concentrated nitric acid solution that should be used to prepare 250 mL of 2.0 M HNO₃ would be

What is the mole fraction of the solute in a 1.00 molal aqueous solution?

6.02x10²⁰ molecules of urea are present in 100mL of its solution. The concentration of the solution is

Which of The following has a maximum number of molecules?

The number of moles of KMnO₄ reduced by one mole of KI in an alkaline medium is- 

The number of moles of oxygen in 1L of air containing 21% oxygen by volume, under standard conditions, is 

What volume of  oxygen gas (O₂) measured at $0°\mathrm{C}$ and 1 atm, is needed to burn completely 1L of  propane gas (C₃H₈) measured under the same conditions?

1 g of magnesium is burnt with 0.56g of oxygen in a closed vessel.The surplus reactant and its quantity are

(At. weight of Mg = 24, O=16)

Percentage of Se in peroxidase anhydrase enzyme is 0.5% by weight (at. weight = 78.4), then minimum molecular weight of peroxidase anhydrase enzyme is

Number of moles of Mn${\mathrm{O}}_4^{-}$ required to oxidise one mole of ferrous oxalate completely in acidic medium will be 

The total number of valence electrons in 4.2g of ${\mathrm{N}}_3^{-}$ ion is (N_A is the Avogadro's number)

When 22.4L of H₂(g) is mixed with 11.2L of Cl₂(g) each at STP, the moles of HCl(g) formed is equal to 

The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (at. mass of Al = 27)

In the Haber process, 30 L of dihydrogen and 30L of dinitrogen were taken for the reaction, which yielded only 50% of the expected product. What will be the composition of the gaseous mixture under the said conditions in the end?

The number of atoms in 4.25 g of NH₃ is approximately

In the reaction, 4NH₃(g)+ 5O₂(g) $\to$4NO(g) +6H₂O(l)

When 1 mole of ammonia and 1 mole of O₂  reacts to completion, then

An element X has the following isotopic composition:

²⁰⁰X : 90%, ¹⁹⁹X : 8.0%, ²⁰²X : 2.0%

The weighted average atomic mass of the naturally occurring element X is closest to 

0.24g of a volatile gas, upon vaporisation, gives 45 mL vapour at NTP. What will be the vapour density of the substance?

(Density of H₂ = 0.089)

The hydrated salt, Na₂SO₄.nH₂O, undergoes a 55% loss in mass on heating and becomes anhydrous. The value of n will be:

12 g of Mg (atomic mass = 24) will react completely with an acid to give:

The molality of a 15% (w/vol.) solution of H₂SO₄ of density 1.1g/cm³ is-

Which mode of expressing concentration is independent of temperature?

The product of atomic mass and specific heat of metal is approximately 6.4. This was given by:

A metal M forms a compound M₂HPO₄. The formula of the metal sulfate is:

A partially dried clay mineral contains 8% water. The original sample contained 12% water and 45% silica. The percentage of silica  in the partially dried sample is nearly:

One litre N₂, 7/8 litre O₂ and 1 litre CO are taken in a mixture under indentical conditions of P and T. The amount of gases present in mixture is given by:

Equal volumes of 0.1 M AgNO₃ and 0.2 M NaCl are mixed. The concentration of N${\mathrm{O}}_3^{-}$ ions in the mixture will be:

A solution contains Na₂CO₃ and NaHCO₃. 10 mL of the solution required 2.5 mL of 0.1 M H₂SO₄ for neutralisation using phenolphthalein as indicator. Methyl orange is then added when a further 2.5 mL of 0.2 M H₂SO₄ was required. The amount of Na₂CO₃ and NaHCO₃ in 1 litre of the solution is: