The mass of an atom of nitrogen is _______.

In a sodium atom (atomic number = 11 and mass number = 23) and the number of neutrons is _______.

In halogens, which of the following, increases from iodine to fluorine?

The species CO, CN^- and N₂ are ______.

Viscosity of a liquid is a measure of

An isochoric process takes place at constant ______.

A catalyst will increase the rate of a chemical reaction by ______.

Which of the following halogens do not exhibit a positive oxidation number in their compounds?

Hydrogen peroxide is used as

Which one of the following alkaline earth metal carbonates is thermally most stable

Boron has an extremely high melting point because of

In the organic compound CH₂=CH-CH₂-CH₂-C\(\equiv \)CH,  the pair of hydridised orbitals involved in the formation of: C₂ - C₃ bond is _____.

Which conformation of ethane has the lowest potential energy?

Express the following in the scientific notation:
(i) 0.0048
(ii) 234,000
(iii) 8008
(iv) 500.0
(v) 6.0012

What type of metals are used in photoelectric cells? Give one example.

Which of the following pairs of elements would have a more negative electron gain enthalpy? F or Cl

Calculate the temperature at which the average speed of oxygen equals to that of hydrogen at 20 K

Find out the value of equilibrium constant for the following reaction at 298 K.
\(2 \ NH_{ 3 }(g)+CO_{ 2 }(g)\leftrightharpoons NH_{ 2 }CONH_{ 2 }(aq)+H_{ 2 }O(l)\)
Standard Gibbs energy change,  \(\Delta G^{ \circ }\) at the given temperature is -13.6 kJ mol^-1.

One millilitre solution of 0.01M HCl is added to 1L of sodium chloride solution.What will be the pH of the resulting solution?

Assign oxidation number to the underlined elements in each of the following species - CaO₂

What is the difference between the terms 'hydrolysis' and 'hydration'?

Name the compounds used for the manufacture of washing soda by Solvay process

If B-CI bond has a dipole moment, explain why BCl₃ molecule has zero dipole moment.

For the following bond cleavages, use curved-arrows to show the electron flow and classify each as homolysis or heterolysis. Identify reactive intermediate produced as free radical, carbocation and carbanion.

How would you convert the following compounds to benzene?
Benzoic acid

What are pesticides?

The uncertainty in the position and velocity of a particle are 10^-10 m and 5.27 x 10^-24 ms^-1respectively. Calculate the mass of the particle.

Consider the ground state electronic configration given below
1s²2s²2p⁶3s²
i. Identify the configration which is associated with the lowest and higest ionisation enthalpy?
ii. Arrange the above configration in order of increasing negative electrons gain enthalpy.

Write short notes on 
\(\sigma \quad and\quad \pi -\quad bonds\quad \)

Calculate the critical constants of a gas whose van der Waals' constants are \(a=0.751L^{ 2 }\ atm\ mol^{ -2 }\ and\ b=0.0226\ L\ mol^{ -1 }\)

The enthalpy of formation of methane at constant pressure and 300 K is - 78.84 kJ. What will be the enthalpy of formation at constant volume?

Find out the value of K_c for each of the following equilibria from the value of K_p:
(a) \(2 \mathrm{NOCl}(\mathrm{g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g})+\mathrm{Cl}_{2}(\mathrm{~g}) ; K_{p}=1.8 \times 10^{-2} \text { at } 500 \mathrm{~K}\)
(b) \(CaCO_{ 3 }(s)\leftrightharpoons CaO(s)+CO_{ 2 }(g); { K }_{ p }=167at1073 \ K\)

The standard electrode potentials at 298 K are given below
\({ E }_{ { { Zn }^{ 2+ } }/Zn }^{ o }=-0.76\quad V,\quad { E }_{ { Fe }^{ 2+ }/Fe }^{ o }=-0.44\quad V,\\ { E }_{ { { H }^{ + } }/{ H }_{ 2 } }^{ o }=-0.0\quad V,\quad { E }_{ { Cu }^{ 2+ }/Cu }^{ o }=+0.34\quad V\)
Which of the following two electrodes should be combined to form a cell having highest emf?
Identify the cathode and the anode and write the cell reaction.
Also mention the direction of flow of electrons in the external as well as the internal circuit.

Complete the reaction (Write balanced equation) \({ Fe }_{ 3 }{ O }_{ 4 }+{ H }_{ 2 }\longrightarrow \)

What happens when sodium hydrogen carbonate is heated

Explain Silicon dioxide is treated with hydrogen fluoride.

Give a brief description of the principles of the following techniques taking an example in each case: Chromatography.

Convert 1,2-dibromoethane into ethyne.

It is advised not to sleep in a closed room with burning coke angithi to warm up. Explain.

Calculate
(5.7 x 10^-5) \(\div \) (4.2 x 10^-3)

Wilhelm Rontgen showed that when electrons strike a material in the cathode ray tube, some rays are originated that can cause fluorescence in the fluorescent material placed outside the cathode ray tubes. He named these rays as X-rays as these were not deflected by electric and magnetic field. X-rays are used as a diagnostic tool in the treatment of disease and bone fracture. An intelligence officer, John catched a smuggler by using this X-ray machine. He was trying to smuggle the drugs while travelling abroad.
The approximate wavelength of X-rays is ............

Expalin what is meant by the ionisation energy of an elements . How does this vary between hydrogen and neon in the periodic table ?Discuss how the variation can be related to the electronic structure of the atoms.

One day when Ravi was passing by his laboratory and felt some suffocating odour. He saw his laboratory attendant was preparing some chemical, named as ammonia. Suddenly, he saw that some chemical had fallen at the hand of the attendant. He run at once and take some highly diluted HCl and apply at the burned place.By this the attendent got relief.
Can you predict and draw the structures of these compound.Also mark the central atom and find out the bond pairs and lone pairs.

An iron cylinder contains helium at a pressure of 250 KPa at 300 K. The cylinder can withstand a pressure of \(1\times { 10 }^{ 6 }Pa\) . The room in which cylinder is placed catches fire. Predict whether the cylinder will blow up before it melts or not (mp of the cylinder = 1800 K).

Mr.sharma, who was a teacher,explained the second law of thermodynamics by giving example of car in which heat energy produced by the combusion of a fuel is not completely converted into mechanical work.He also explained the working of refrigerator on the basis of this law.
(i) State the second law of thermodynamics
(ii) why the energy produced by the combustion of a fuel in the car engine is not completely converted into mechanical work?
(iii)  could you explain the working of refrigerator on the basis of second law of thermodynamics?
(iv) What values are associated with Mr.Sharma?

Rahul and Rohan was friends. Rahul's father was a great scientist. One day Rohan told Rahul that he is suffering from goitre so doctor advised him to use iodised salt in food. Rahul asked his father how can we check the presence of iodine in a salt, who explained him the titrimetric method to check the presence of iodine in the salt.
Find the oxidation state of each element in the reagent used to check the presence of iodine.

Scientist of UK has designed the cars, working on hydrogen fuel cells instead of petrol engines. Here hydrogen is used as sources of electrical energy i.e. a reaction of hydrogen and oxygen is used to generate electrical energy. It has many advantages over the conventional fossil fuels and electric power generation.
Give two advantages of hydrogen over fossil fuels?

Explain why ?
Mg₃N₂ when reached with water gives off NH₃ but HCl is not obtained from msCl On reaction with water at room temperature

Diamond is covalent, yet it has high melting point, why?

On complete combustion, 0.246 g of an organic compound gave 0.198g of carbon dioxide and 0.1014g of water. Determine the percentage composition of carbon and hydrogen in the compound.

Which of the following compounds will show cis-trans isomerism?
CH₂= CBr₂

250 mL of 0.5 M sodium sulphate (Na₂SO₄) solution are added to an aqueous solution containing 10.0 g of BaCl₂ resulting in the formation of white precipitate of BaSO₄. How many moles and how many gram of barium sulphate will be obtained?

The quantum numbers of six electrons are given below. Arrange them in order of increasing energies. If any of these combination(s) has/have the same energy lists:
1. n = 4, l = 2, ml = –2 , ms = –1/2
2. n = 3, l = 2, ml = 1 , ms = +1/2
3. n = 4, l = 1, ml = 0 , ms = +1/2
4. n = 3, l = 2, ml = –2 , ms = –1/2
5. n = 3, l = 1, ml = –1 , ms = +1/2
6. n = 4, l = 1, ml = 0 , ms = +1/2

Justify the given statement with suitable examples "the properties of the elements are a periodic function of their atomic number".

In each of the following pairs, predict which has higher value of the property mentioned and why?
NF₃,NH₃  Dipole moment

A large flask fitted with a stop-cock is evacuated and weighted; it mass is found to be 134.567g. It is then filled to a pressure of 735 mm at 31^oC with a gas of unknown molecular mass and then reweighted; it mass is 137.456 g. The flask is then filled with water and weighed again; its mass is now 1067.9 g. Assuming that the gas is ideal, calculate the molar mass of the gas.

Two moles of a perfect gap undergo the following processes.
(i) a reversible isobaric expansion from (1.0 atm, 20.0 L) to (1.0 atm, 40.0 L)
(ii) a reversible isochoric change of state from (1.0 atm, 40.0 L) to (0.5 atm, 40.0 L)
(iii) a reversible isothermal compression from (0.5 atm, 40.0 L) to (1.0 atm, 20.0 L)
Answer the question related to the above processes.
Calculate the total work (W) and the total heat change (q) involved in the above processes.

What is the pH of 0.001M aniline solution? The ionization constant of aniline can be taken from Table . Calculate the degree of ionization of aniline in the solution. Also calculate the ionization constant of the conjugate acid of aniline.

Justify giving reactions that among halogens, fluorine is the best oxidant and among hydrohalic compounds, hydroiodic acid is the best reductant.

Give ion electron equations for the reactions.
Oxidation of ferrocyanide ions to ferricyanide ions in acidic medium.

How will you prepare the following ?
(v)   Water glass

What happens when
i)Carbon monoxide gas is passed over heated iron oxide?

Give condensed and bond line structural formulas and identify the functional group(s) present, if any, for :
(a) 2,2,4-Trimethylpentane
(b) 2-Hydroxy-1,2,3-propanetricarboxylic acid
(c) Hexanedial

Explain the mechanism of sulphonation and nitration of benzene

Give the main points of the plan made by Government of India to save Taj Mahal.