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Champ Jee
Subject: Chemistry
, asked on 20/5/18
Please explain the answer!
This is from Meritnation test.
Answer
3
Champ Jee
Subject: Chemistry
, asked on 18/5/18
Confused!?
If one mole is given, it means it's volume is 22.4 litres. To find mass we should multiply density and volume?!? But not given in any options!
Q.38. The weight of 1 mole of a gas of density 0.1784 g
${L}^{-1}$
at NTP is -
(1) 0.1784 g
(2) 1 g
(3) 4 g
(4) Can not be Calculate
Answer
2
Champ Jee
Subject: Chemistry
, asked on 22/4/18
Solve this :
Ans is 4, right.
Coz: 32x/2000 * 100 = 6.4,
Solving this x=4.
Am I right?
Q. Insulin contain 6.4% Sulphur by mass then calculate no. of Sulphur atoms in 1 mole of insulin if molecular mass is 2000 g.
Answer
2
Champ Jee
Subject: Chemistry
, asked on 21/4/18
Que in pic.
Should we take moles of P atoms= moles of P molecules.
I didn't understand this que. Please elaborate the explanation as much as you can.
Q. A sample of potato starch was ground in a ball mill to give a starchlike molecule of lower molecular weight. The product analysed 0.086 % phosphorus. If each molecule is assumed to contain one atom of phosphorus, what is the molecular weight of the material?
(3.6 × 10
^{4}
amu)
Answer
1
Champ Jee
Subject: Chemistry
, asked on 19/4/18
Ans key shows : option c)
Q. Atoms
1. (S)
If we consider that 1/6 in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will
(a) decrease twice
(b) increase two fold
(c) remain unchanged
(d) be a function of the molecular mass of the substance
Answer
1
Champ Jee
Subject: Chemistry
, asked on 19/4/18
Q23.
Ans key shows option (b).
Q.23. If the atomic weight of carbon were set at 24 amu, the value of the Avogadro constant would be
(a) 6.022
$\times {10}^{23}$
(b) 12.044
$\times {10}^{23}$
(c) 3.011
$\times {10}^{23}$
(d) none of these
Answer
1
Champ Jee
Subject: Chemistry
, asked on 19/4/18
Q14.
Ans given as : option b.
Q.14. 1 mole of a diatomic element
${X}_{2}$
contains 34 and 40 moles of electrons and neutrons respectively. The isotopic formula of the element is
(a)
${}_{34}{}^{74}X$
(b)
${}_{17}{}^{37}X$
(c)
${}_{34}{}^{40}X$
(d)
${}_{20}{}^{40}X$
Answer
1
Champ Jee
Subject: Chemistry
, asked on 19/4/18
Q.28. 600 mL of a mixture of
${O}_{3}and{O}_{2}$
weighs 1 g at NTP. Calculate the volume of ozone in the mixture.
(200 mL)
Answer
4
Champ Jee
Subject: Chemistry
, asked on 18/4/18
Q. The density of a particular crystal of LiF is 2.65 g/cc. X-ray analysis shows that
$L{i}^{+}and{F}^{-}$
ions are arranged in a cubic array at a spacing of 2.01
$\stackrel{\circ}{A}$
. From these data calculate the apparent Avogadro constant.
[Li=6.030, F=18.998 (1
$\stackrel{\circ}{A}$
=
${10}^{-8}$
cm)]
Answer
1
Champ Jee
Subject: Chemistry
, asked on 15/4/18
After dividing 224 by 56, we get total moles, right? And 1 mole has 6.022*10^23 atoms. So why did the expert stop after 4 moles at 4 atoms in haemoglobin? Please elaborate the concept behind it.
Answer
1
Champ Jee
Subject: Chemistry
, asked on 15/4/18
The density of mercury is 13.6 g/cc. Calculate approximately the diameter of an atom of mercury, assuming that each atom is occupying a cube of edge length equal to the diameter of the mercury atom.
Answer
1
Champ Jee
Subject: Chemistry
, asked on 15/4/18
Q. If the components of air are
${N}_{2},78\%;{O}_{2},21\%;Ar,0.9\%andC{O}_{2},0.1\%byvolume,whatwouldbethemolecularweightofair?$
Answer
1
Champ Jee
Subject: Chemistry
, asked on 12/4/18
Why is relative no. of atoms of moles = percentage of that element in compound/atomic mass?? How??
Like given in pic!
Answer
2
Champ Jee
Subject: Chemistry
, asked on 11/4/18
Example- 40 Calculate the empirical formula of a compound that contains 26.6% potassium, 35.4% chromium and 38.1% oxygen [Given K = 39.1; Cr = 52; O = 16]
Sol. Element Percentage Atomic mass
Potassium 26.6 39.1
Chromium 35.4 52.0
Oxygen 38.1 16.0
Relative no. Simplest ratio Simplest whole no. ratio
of atoms
$\begin{array}{ccc}\frac{26.6}{39.1}=0.68& \frac{0.68}{0.68}& 1\times 2=2\\ \frac{35.4}{52}=0.68& \frac{0.68}{0.68}& 1\times 2=2\\ \frac{38.1}{16}=2.38& \frac{2.38}{0.68}& 3.5\times 2=7\end{array}$
Therefore emperical formula is
${K}_{2}C{r}_{2}{O}_{7}$
.
Answer
1
Champ Jee
Subject: Chemistry
, asked on 10/4/18
How
no. of moles = percentage of mass / molar mass ??
Please explain!
Answer
1
1
2
3
4
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What are you looking for?

This is from Meritnation test.

If one mole is given, it means it's volume is 22.4 litres. To find mass we should multiply density and volume?!? But not given in any options!

Q.38. The weight of 1 mole of a gas of density 0.1784 g ${L}^{-1}$ at NTP is -

(1) 0.1784 g

(2) 1 g

(3) 4 g

(4) Can not be Calculate

Ans is 4, right. Coz: 32x/2000 * 100 = 6.4, Solving this x=4. Am I right?Solve this :Q. Insulin contain 6.4% Sulphur by mass then calculate no. of Sulphur atoms in 1 mole of insulin if molecular mass is 2000 g.

Should we take moles of P atoms= moles of P molecules.

I didn't understand this que. Please elaborate the explanation as much as you can.

Q. A sample of potato starch was ground in a ball mill to give a starchlike molecule of lower molecular weight. The product analysed 0.086 % phosphorus. If each molecule is assumed to contain one atom of phosphorus, what is the molecular weight of the material?

(3.6 × 10

^{4}amu)Q. Atoms

If we consider that 1/6 in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will1. (S)

(a) decrease twice

(b) increase two fold

(c) remain unchanged

(d) be a function of the molecular mass of the substance

Ans key shows option (b).

Q.23. If the atomic weight of carbon were set at 24 amu, the value of the Avogadro constant would be

(a) 6.022$\times {10}^{23}$

(b) 12.044 $\times {10}^{23}$

(c) 3.011 $\times {10}^{23}$

(d) none of these

Ans given as : option b.

Q.14. 1 mole of a diatomic element ${X}_{2}$ contains 34 and 40 moles of electrons and neutrons respectively. The isotopic formula of the element is

(a) ${}_{34}{}^{74}X$

(b) ${}_{17}{}^{37}X$

(c) ${}_{34}{}^{40}X$

(d) ${}_{20}{}^{40}X$

(200 mL)

Q. The density of a particular crystal of LiF is 2.65 g/cc. X-ray analysis shows that $L{i}^{+}and{F}^{-}$ ions are arranged in a cubic array at a spacing of 2.01 $\stackrel{\circ}{A}$. From these data calculate the apparent Avogadro constant.

[Li=6.030, F=18.998 (1 $\stackrel{\circ}{A}$ = ${10}^{-8}$cm)]

Q. If the components of air are ${N}_{2},78\%;{O}_{2},21\%;Ar,0.9\%andC{O}_{2},0.1\%byvolume,whatwouldbethemolecularweightofair?$

Like given in pic!

Sol. Element Percentage Atomic mass

Potassium 26.6 39.1

Chromium 35.4 52.0

Oxygen 38.1 16.0

Relative no. Simplest ratio Simplest whole no. ratio

of atoms

$\begin{array}{ccc}\frac{26.6}{39.1}=0.68& \frac{0.68}{0.68}& 1\times 2=2\\ \frac{35.4}{52}=0.68& \frac{0.68}{0.68}& 1\times 2=2\\ \frac{38.1}{16}=2.38& \frac{2.38}{0.68}& 3.5\times 2=7\end{array}$

Therefore emperical formula is ${K}_{2}C{r}_{2}{O}_{7}$.

no. of moles = percentage of mass / molar mass ??

Please explain!