Archives

what energy photon is necessary to raise an electron in hydrogen from the n = 1 to the n = 3 energy level?

Energy of nth excited state is En = − 13.6/n2 The energy absorbed is equal to the difference between these two energy levels, i.e. the energy... View Article

The correct order of strength of acidity of the following compounds is

Answer The presence of electron withdrawing groups, such as nitro, increases the acidic strength of phenol, whereas the presence of electron... View Article

If the distance between Na+ and Cl− ions in a sodium chloride crystal is X pm, the length of the edge of the unit cell is

Chloride ions at the corner and sodium ions at the edge centre touch each other in the fcc unit cell of NaCl along a specific edge.As a result,... View Article

The rate constant of a reaction depends on temperature, initial concentration of the reactants, time of reaction, extent of reaction

The rate constant of a reaction increases as the temperature rises, but it is unaffected by the initial concentration of reactants, reaction... View Article

Which of the ethers will produce methyl alcohol on treatment with hot concentrated HI?

When tert butyl methyl ether is treated with hot concentrated HI, it produces methyl alcohol. Tert butyl iodide is the other product.... View Article

Which of the following ions has the least flocculation value Cl−, SO2−4, PO3−4, [Fe(CN)6]4−

The higher the valence of the flocculating ion added, the more powerful it is in causing precipitation. This is referred to as the Hardy-Schulze... View Article

The correct order of the O−O bond length in O2,H2O2 and O3 is

The bond length of O−O in H2O2 is 147.5pm, in O3 is 128pm and in O2 it is 121pm, so the correct order is O2<O3<H2O2.... View Article

The hexaaquomanganese (II) ion contains five unpaired electrons while the hexacyano ion contains only one unpaired electron.

The electronic configuration of Mn(II) is 3d54s0. The ligand connected to the metal in the instance of hexaaquomanganese (II) ion is water, which... View Article

1ch4 4cl2 =ccl4 4hcl find equivalent mass

The number of g equivalent weight of CH4 is equal to the number of g equivalent weight of HCl, according to the law of equivalence. The law of... View Article

the electronic configuration of an element is [ne]3s2 3p3. what is the atomic number of the element which is just below the above element in the periodic table? *1 point

The element which present just below this element will have outermost electronic configuration as 4s24p3, so its full electronic configuration is... View Article

which of the following is most reactive towards hcn

Acetone Formaldehyde Acetaldehyde Diethyl Ketone Answer The addition reaction of hydrogen cyanide to create cyanohydrin is most... View Article

what is the weight of available oxygen from a solution of h2o2, if 20 ml of this solution needs 25 ml, N/20 kmno4 for complete oxidation?

Hydrogen peroxide reacts with potassium permanganate to get converted to oxygen as potassium permanganate is a very strong oxidizing agent that... View Article

the density of ethanol 60 y wiegth is 0.8937 g/ml what is mlarity

The weight percentage or %w/w represents the weight ratio of solute and the solution.Molarity = Moles of solute/Volume of solution(L) Formula for... View Article

How many of the following can react with bases? (1) Al2O3 (2) MgO (3) BeO (4) SeO2 (5) NO2 (6) PbO (7) As2O3

Answer: An amphoteric compound is a molecule or ion that can react both as an acid and as a base. Since water has the potential to act both as... View Article

for the elementary reaction, 2a b → products, the active mass of b is kept constant, and that of a is doubled. the rate of reaction will be

On doubling the active mass of A the rate of reaction increases 4 times. Rate = K[A]2[B]... View Article

100 ml of tap water containing ca(hco3)2 was titrated with n/50hcl with methyl orange as indicator. it 30 ml of hcl were required, what is the degree of temporary hardness as ppm.

Milli equivalent of Ca(HCO3)2 = miili equivalent of CaCO3 = mili equivalent of HCl N1V1 = N2V2 1000 × w/(100/2) = 30/50 w= 0.03 g For 100ml... View Article

Reema took 5ml of lead nitrate solution in a beaker and added approximately 4ml of potassium iodide solution to it. what would she observe?

The relation between lead nitrate and potassium iodide is an example of precipitation reaction. Pb (NO3)2 + 2 KI ⟶ ⟶ PbI2 + 2KNO3 (yellow ppt)... View Article

ASSERTION : Reducing character of hydrides of group 16 elements increases as the atomic number of central atom increases. REASON: Due to strong force of attraction of H-E bond

From top to bottom, the size of the elements and their atomic number rise in group 16. The bond energy or force of attraction of the H-E... View Article

In which case is the number of molecules of water maximum?A. 10−3 mol of water.B. 0.00224 L of water vapour at 1 atm and 273 k.C. 0.18 g of water. D. 18 ml of water.

We must first determine the molar mass of water. Water's molecular formula is H2O. 2(molar mass of hydrogen)+molar mass of oxygen Equals... View Article

the freezing point of aqueous solution that contains 5 y mass urea, 1.0 y mass kcl and 10 y mass of glucose is

ΔTf = ΔTf(glucose)+ΔTf(KCl)+ΔTf(urea) But ΔTf = (Kf×W2/M2×W2)×1000 Therefore, [1000×1.86×10/100×180] + [1000×1.86×1×2/74.5×100] +... View Article