How many neutrons and protons are there in the following nuclei?
We know atomic number(z) = no of protons = no of electrons
Also mass number(A) = no of protons + no of neutrons
136C:
Here mass number = 13
Atomic number = Number of protons = 6
Number of neutrons = (mass number) – (Atomic number)
= 13 – 6 = 7
:
Here mass number = 16
Atomic number = 8 Number of protons = 8 Number of neutrons = (mass number) – (Atomic number)
= 16 – 8 = 8
:
Here Mass number = 24
Atomic number = Number of protons = 12
Number of neutrons = (mass number) – (Atomic number)
= 24 – 12 = 12
:
Here mass number = 56
Atomic number = Number of protons = 26
Number of neutrons = (mass number ) – (Atomic number)
= 56 – 26 = 30
:
Here mass number = 88
Atomic number = Number of protons = 38
Number of neutrons = (mass number) – (Atomic number)
= 88 – 38 = 50
The mass of an electron is 9.1 × 10–31 kg. If its K.E. is 3.0 × 10–25 J, calculate its wavelength.
Calculate the amount of carbon dioxide that could be produced when
(i) 1 mole of carbon is burnt in air.
(ii) 1 mole of carbon is burnt in 16 g of dioxygen.
(iii) 2 moles of carbon are burnt in 16 g of dioxygen.
Calculate the wavelength of an electron moving with a velocity of 2.05 × 107 ms–1.
Balance the following redox reactions by ion – electron method :
(a) MnO4 – (aq) + I – (aq) → MnO2 (s) + I2(s) (in basic medium)
(b) MnO4 – (aq) + SO2 (g) → Mn2+ (aq) + HSO4– (aq) (in acidic solution)
(c) H2O2 (aq) + Fe 2+ (aq) → Fe3+ (aq) + H2O (l) (in acidic solution)
(d) Cr2O7 2– + SO2(g) → Cr3+ (aq) + SO42– (aq) (in acidic solution)
In a process, 701 J of heat is absorbed by a system and 394 J ofwork is done by the system. What is the change in internal energy for the process?
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
In a reaction A + B2 → AB2 Identify the limiting reagent, if any, in the following reaction mixtures.
(i) 300 atoms of A + 200 molecules of B
(ii) 2 mol A + 3 mol B
(iii) 100 atoms of A + 100 molecules of B
(iv) 5 mol A + 2.5 mol B
(v) 2.5 mol A + 5 mol B
At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?
Which one of the following will have largest number of atoms?
(i) 1 g Au (s)
(ii) 1 g Na (s)
(iii) 1 g Li (s)
(iv) 1 g of Cl2(g)
Density of a gas is found to be 5.46 g/dm3 at 27 °C at 2 bar pressure. What will be its density at STP?
Write the complete symbol for the atom with the given atomic number (Z) and Atomic mass (A)
(i) Z = 17, A = 35
(ii) Z = 92, A = 233
(iii) Z = 4, A = 9
(i) Calculate the total number of electrons present in one mole of methane.
(ii) Find
(a) the total number and
(b) the total mass of neutrons in 7 mg of 14C. (Assume that mass of a neutron = 1.675 × 10–27 kg).
(iii) Find
(a) the total number and
(b) the total mass of protons in 34 mg of NH3 at STP.
Will the answer change if the temperature and pressure are chang
An atom of an element contains 29 electrons and 35 neutrons.
Deduce (i) the number of protons and (ii) the electronic configuration of the element.
How do you expect the metallic hydrides to be useful for hydrogen storage? Explain.
Consider the following species:
N3–, O2–, F–, Na+, Mg2+ and Al3+
(a) What is common in them?
(b) Arrange them in the order of increasing ionic radii.
Thermodynamically the most stable form of carbon is
(a) diamond (b) graphite (c) fullerenes (d) coal
For an isolated system, ΔU = 0, what will be ΔS?
In astronomical observations, signals observed from the distant stars are generally weak. If the photon detector receives a total of 3.15 × 10–18 J from the radiations of 600 nm, calculate the number of photons received by the detector.
Write balanced equations for reactions between
(a) Na2O2and water
(b) KO2 and water
(c) Na2O and CO2
What is meant by the conjugate acid-base pair? Find the conjugate acid/base for the following species:
HNO2, CN– , HClO4, F –, OH–, CO2–3 and S-
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