Chemistry Short Questions Guess Paper 11th Class 2017
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Frequently Asked Questions (2012 to 2016)
Chemistry Short Questions Variations
Define Fahrenheit scale.
What is conjugate base of the acid? OR A weak acid has strong conjugate base. Justify.
Define Evaporation, OR Explain why evaporation takes place at all temperatures.
Define hydrolysis with example. OR Differentiate between hydration and hydrolysis.
Voltaic cell is reversible cell, State.
What are isotopes? Why they have same chemical but different physical properties?
What is mole? OR Why the sum of mole fractions of all components of a solution is always equal to unity?
What is the basic principle of crystallization?
Define amorphous solids.
Define the octet rule.
Define state of Equilibrium.
Define optimum pH?
What is Lyman series?
Define Balmer series.
What is vaccum distillation?
Define unit cell.
Define vander wall’s equation.
Why is HF a weaker acid than HC1?
Justify that heat of formation of compound is sum of all the other enthalpies.
Calculate the density of methane at STP.
Why regular air cannot be used in diver’s tank?
What is the first law of thermodynamics?
What are London dispersion forces?
What do you mean by chemical equilibrium?
Give two statements of Raoult’s law.
The dipole moments of CO2 and CS2 are zero but that of SO2 is 1.61D. OR Why the dipole moment of SO2 is 1.61 D but that of SO3 is zero? OR What are dipole-dipole forces of attraction? Explain with an example.
What is the basic assumption of VSEPR theory, and discuss the shape of a molecule (BF3) containing three electron pairs? OR Write down two postulates of VSEPR theory. OR State the geometry of NH3 molecule on the basis of VSEPR theory.
Define the term state function, give two examples.
Explain the term enthalpy. OR Explain the term enthalpy of atomization. OR The enthalpy of neutralisation of all the strong acids and strong bases has the same value. Justify. OR State enthalpy of combustion with example.
State Le-Chatelier’s principle and discuss the effect of change in concentration of a product on reversible reaction.
Explain the term buffer capacity. OR What are buffer solutions? How a basic buffer can be prepared? OR Write two uses of buffer solution.
Give the two applications of the solubility product. OR How the type of bonding affects solubility of compounds? OR Define solubility product. Give its one application.
Depression in freezing point is a colligative property. Justify. OR Why Beckmann’s thermometer is used to measure the depression in freezing point?
What is meant by molality? Give its formula.
Why the NaCt and KNO3 are used to lower the melting point of ice?
What is electrochemical series? OR How electrochemical series help us in determining the chemical reactivity of metals?
Lead accumulators is a chargeable battery. Justify. OR What is difference between cell and battery?
Differentiate between average rate and instantaneous rate. OR What is specific rate constant or velocity constant? OR Why different liquids evaporate at different rates even at the same temperature? OR How surface area affects the rate of a chemical reaction? OR What happens to the rate of a chemical reaction with the passage of time?
What are enzymes? Give two examples in which enzymes act as catalyst. OR Enzymes are specific in action. Justify.
Why theoretical yield is greater than actual yield?
Law of conservation of mass has to be obeyed during stoichiometric calculation, give reason. OR Write down stoichiometric assumptions.
What is vapour pressure? OR What is Dalton’s law of partial pressure? OR Write down the values of atmospheric pressure in four different units. OR Lowering of vapor pressure is colligative property. Explain. OR What will be the effect of change of pressure on the synthesis of NH3? OR Derive the units for gas constant R in general gas equation when pressure is in Nm-2 and volume in m3.
What is the size of atom? OR Why cationic radius radius is smaller than parent atom? OR What are defects in Rutherford’s atomic model? OR Why the radius of an atom cannot be determined precisely? OR Mg atom is twice heavier than that of carbon atom. Justify. OR Why is the -radius of a cation smaller than its parent atom? OR The radius of first orbit of hydrogen atom is 0.529 A°. Calculate the radius of 3″1 orbit of hydrogen atom.
What are the defects in Rutherford’s atomic model?
Write the electronic configuration of Cr for which atomic number is 24.
Give the chemistry of electrolysis of aqueous solution of sodium chloride. OR Write electrode reactions of electrolysis of fused sodium chloride.
Define autocatalysis with an example.
Give assumption of stoichiometry.
Why is there a need to crystallize the crude product?
What are isotherms?
Define Avogadro’s law.
Define transition temperature with an example. OR Transition temperature is the term used for elements as well as compounds. Explain.
Write down the electronic configuration of Fe (26) and Br (35).
Give any two properties of neutrons. OR How neutrons were discovered by Chadwick? Give the equation of nuclear reaction involved.
State Hund’s rule and give an example.
What do you know about internal energy of a system? OR Define activation energy and activated complex. OR What is lattice energy? Give an example.
What is electrolytic cell? OR What is the difference between metallic conduction and electrolytic conduction? OR Differentiate between electrolytic and voltaic cell. OR Impure copper can be purified by electrolytic process. Explain.
Define standard electrode potential.
Give chemical reactions taking place at anode and cathode in a fuel cell. OR How fuel cells produce electricity?
Write down any two characteristics of enzyme catalysis.
Define order of reaction. Give one example. OR What is half life method for the determination of order of a reaction? OR Differentiate between Enothermic and Endothermic Reaction. OR Define half life period. How is it used to determine the order of reaction? OR How the values of equilibrium constant helps to predict the direction of a reversible reaction? OR Differentiate between endothermic and exothermic reactions. OR The sum of the coefficients of a balanced chemical equation is not necessarily important to give the order of reaction justify. OR How the direction of a reversible reaction at any instant can be determined by Kc value? OR Radioactive decay is first order reaction. Justify. OR How the value of K, of a reaction helps to predict the direction of a reversible reaction? OR Define a spontaneous reaction. OR Define order of reaction with the help of an example. OR Write a nuclear reaction for the decay of free neutron. OR Write down nuclear reactions involved in the conversion of Cu into Zn.
Why oxygen cannot be determined directly in combustion analysis? OR Write function of Mg (C CO-4)2 and KOH in combustion analysis.
Define molecular ion, write its uses. OR Differentiate between inter molecular forces. OR Differentiate between ion and molecular ion.
What iS Boiling point? OR Why boiling point of H2O is greater than HF? OR Boiling needs a constant supply of heat, why? OR Why the boiling points of noble gases increase down the group?
State Moseley’s law. OR Write two importance of Moseley law.
Define Pauli’s Exclusion Principle with an example. OR State Auf-bau principle and Pauli’s exclusion principle. OR State Pauli Exclusion Principle and Hunt’s rule.
What is common ion effect? Give an example. OR Differentiate between Zeeman effect and stark effect. OR State Joule Thomson effect. Write its application.
Give statement of ‘Distribution Law’.
The electrical conductivity of metals decrease with the increase in temperature. Why? OR Define upper consulate temperature with example.
Mention two defects of Bohr’s model. OR According to Bohr’s model’ in which orbit electron can move?
How the wave nature of electron was verified experimentally? OR Explain electron gas theory.
Differentiate between homogeneous catalysis and heterogeneous catalysis.
What is difference between qualitative analysis and quantitative analysis?
Diamond is insulator and hard. Give reason. OR Diamond is hard and an electrical insulator. Give reason..
State spin quantum number (s) briefly. OR What is Planck’s quantum theory?
Cathode rays are material particles. Explain with reason. OR Why of cathode rays is equal to that of electrons? OR Why the nature of cathode rays is independent of the nature of the gas used in discharge tube? OR Whichever gas is used in the discharge tube, the nature of the cathode rays remains the same. Why? OR How the K-series, L-series and M-series of x-rays spectrum are produced? OR Give reason for the production of positive rays. OR Why — value for the cathode rays is just equal to that of electron?
Define ionization energy and write its variation in the periodic table. OR Name the factors which affect the ionization energy of an element. OR How does ionization energy vary in a group of periodic table? OR Why ionization energy decreases down the group although the nuclear charge increases? OR Define electronegativity. Give its trend in the periodic table.
The bond angles of H20 and NH3 are not 109.5° like that of CH4. Although 0-atom and N-atom are SP3 hybridized like C- in CH4, give reason. OR The bond angles of H2O and NH3 are not 109.5° like that of CH4 although oxygen and nitrogen atoms are SP3 – hybridized. Why? OR Explain the term bond order. OR What is Bond Energy? OR How the nature of a chemical bond is predicted with the help of electronegativity values of two bonded atoms? OR Why n-bonds are more diffused than a-bonds? OR NH 3 and N F Shave different bond angles. Justify. OR Define coordinate covalent bond and give one example. OR it-bonds are more diffused than a-bonds. Give reason. OR Define bond order. Calculate bond order of hydrogen molecule. OR Define bond energy with two parameters which determine its strength.
What is mass spectrum? OR Why atomic spectrum isline spectrum? OR Define spectrums. OR What is the difference between continuous spectrum and line spectrum?
Define empirical formula and molecular formula with example. OR Write four steps for determining empirical formula. OR Define molecular formula of a compound. How is it related with its empirical formula? OR What Gram formula?
What is solvent extraction? OR Write down the name of Eight solvent used in crystallization. OR Define distribution law and how it is helpful in solvent interaction. OR Boiling points of the solvents increase due to the presence of solutes. Justify it. OR Why is the vapour pressure of a solution less than pure solvent?
Calculate the value of R in SI unit. OR Calculate the value of gas constant It in SI-units.
Give four fundamental postulates of kinetic molecular theory of gases. OR Derive Graham’s law of diffusion in the light of kinetic molecular theory of gases. OR Write two faulty assumptions of kinetic molecular theory of gases. OR Write down the faulty postulates of kinetic molecular theory of gases. OR Explain Boyl’s law according to kinetic molecular theory of gases.
Why one feels sense of cooling under the fan after bath? OR Explain with reason, “Evaporation causes cooling.” OR One feels sense of cooling under the fan after bath. Explain with reason.
Write down two applications of liquid crystals. OR Vacuum distillation can be used to avoid decomposition of a sensitive liquid. Explain with reason. OR How the liquid crystals help in the detection of the blockage in veins and arteries?
Define isomorphism and polymorphism with example. OR What is the relationship between polymorphism and allotropy?
Calculate mass of an electfon from its —e value. m OR What is mass spectrometer? OR Define relative atomic mass. OR Define Molar mass. OR State the law of mass action. OR What is Avogadro’s number? Give equation to relate the Avogadro’s number and mass of an element. OR Calculate the mass of electron when its e/m value is 1.7588 x 10’1 C OR Calculate fraction of total pressure exerted by oxygen when equal masses of CH4 and 02 are mixed in an empty container at 25°C. OR Calculate mass in kg of 2.6 x 1020 molecules of SO2. OR No individual neon atom in the sample of the element has a mass of 20.18 amu. Explain with reason.
State Heisenberg’s Uncertainty Principle and give its mathematical expression.
Define orbital. OR Why the energy of antibonding molecular orbital is higher than corresponding bonding molecular orbitals? OR Distribute tk electron in orbitals of 29Cu and 26Fe. OR Justify that the distance gaps between different orbitals go on increasing from the lower to higher orbits. OR Sketch the molecular orbital picture of 02. OR Define Hydrogen Bonding.
State the Hess’s law of constant heat summation. OR Give statement of Hess’s law.
Write two applications of equilibribm constant.
Define pH and p0H.
One mg of K2CrO4 has thrice the number of ions than the number of formula units when ionized in water, justify. OR Water and ethanol can mix in all proportions, give reason. OR What is water of crystallization? Give two examples. OR What is ionic product of water? Define pH. OR One molal solution of urea in water is dilute as compared to one molar solution of urea but the number of particles bf solute is same. Justify it. OR The vapour pressure of diethyl ether is higher than that of water at same temperature. Give reason. OR Gasoline evaporates much faster than water. Give reason. OR Water vapours do not behave ideally at 273 K. Justify. OR What is meant by water of crystallization? Give an example. OR Water vapours do not behave ideally at 273 K. Explain. OR How many molecules of water are there in lOg of ice? OR Ice occupies more space than water, give reason.
Define and write the meaning of chromatography. OR Differentiate between adsorption chromatography and partition chromatography. OR Define chromatography. Give, its two uses. OR Differentiate between stationary and mobile phase used in chromatography. OR What do you know about Rf value of a component in paper chromatography?
Give the importance of sublimation. OR Define sublimation and partition law. OR Define sublimation. What type of a substance can be purified by this technique? OR What is sublimation? Give one example of sublime solid. OR Heat of sublimation of iodine is very high although it is a molecular solid. Give reason.
State Boyle’s law of gases.
Give two applications of plasma. OR What is plasma state? How is plasma formed at high temperature?
Ionic solids do not conduct electricity in solid state. Give reason. OR How the percentage ionic character of a covalent bond is determined by dipole moment? OR No bond in chemistry is 100% ionic. Justify it. OR Why ionic crystals are highly brittle? OR How the electronegativity difference of two bonded atom can be used to predict the ionic/covalent nature of the bond? OR Ionic crystals are highly brittle. Explain with reason. OR Why the ionic radius of Cf- ion increases from 99 pm to 181 pm?
Differentiate between ideal and non-ideal solutions. OR Many solutions do not behave ideally. Give reason.
One molal solution of glucose is dilute as compared to one molar solution of glucose. Justify it. OR What is molarity? Calculate the molarity of a solution containing 9 grams of glucose (C61-11206) in 250 cm3 of solution. OR Define molal boiling constant with an example.
Salt bridge is not required in lead storage call. Why? OR What is the function of salt bridge in galvanic cell?
Write down reactions taking place at the electrodes on the discharging of Nickle-Cadmium Cell.
Calculate the oxidation number of Cr in K2CrO4 and Cr202-2. OR Find out the oxidation state of Mn in (a) KMnO4 (ii) K2MnO4. OR Calculate oxidation number of chromium in CrCt3. OR Calculate the oxidation number of `Mn’ in KMnO4.
Define and give an example of the process of activation of a catalyst. OR What is poisoning of a catalyst? Give an example. OR How a catalyst is specific in its action?
N2 and CO have same number of electrons, protons and neutrons. Justify. OR Why N2 and CO have the same number of protons, electrons and neutrons?
Define the term molecule. Give two examples also. OR Separate the following molecules as polar or non-polar: (i) CO2 (ii) CH3OH (iii) CC Q4 (iv) HF