9th Chemistry Guess Lahore Board

 

Questions # 1

• Give two properties of neutrons.
• How many neutrons are present in C-12 and C-13?
• Do you know any element having no neutrons in its atoms?

Questions # 2

• Why the second ionization energy of an element is higher than first one?
• What do you mean by blocks in a periodic table and why elements were placed in blocks?
• For an element Z = 92, A = 238. Calculate the number of electron and proton in it.
• What is the definition of the element according to the Robert Boyle?
• What is the significance of the symbol of an element?
• Define Boyle’s Law and verify with an example.
• What type of elements from metallic bond?
• Define Avogadro’s number.
• Which element has the highest electro negativity?
• What type of elements have tendency of sharing of electrons?
• Why and how elements arranged in a period?
• What type of elements are metals?
• Write down the names of elements of group 1 with their symbols?
• Define Boyle’s rule?

Questions # 3

• Write two chemical properties of metals and non-metals.
• Define metal, give two examples.
• Write down the name of four least reactive metals.
• Compare any four physical properties of metals and non-metals.
• What are important physical characteristics of metals?
• Why reactivity of metals increase drown the group?
• How non-metals are essential part of our body structure?
• Which metal is used for metal work?
• State the physical properties of metals
• What is the trend of variation it densities of alkali metals?
• Metals are good conductor of electricity. Why?
• What are transition metals?
• How oxygen reacts with group II A metals?

Questions # 4

• Why silver and gold are least reactive?
• Give properties and uses of gold?
• Which is lighter than aluminum of gold?
• Give the applications of silver. Why platinum is used for making Jewellery?
• Can pure gold be used for making electrical wires?

Questions # 5

• Give the Properties of dipole-dipole forces.
• Define dipole interactions. How are they created?

Questions # 6

• Write down any two properties of canal rays.
• Give two properties of positive rays.
• Write down two properties, of cathode rays.
• What conclusion you derive from these properties.
• How are cathode rays produced?
• What is the nature of charge on cathode rays?
• What are its five major characteristics?

Questions # 7

• Define atomic mass unit. Why is it needed?
• Define atomic number and mass number.
• What are SI units of atomic radius?
• Define Tri-atomic and Hetero-atomic.
• Why do atoms react?
• How can you define atomic radius?
• What is Luther Meyer’s atomic volume curve?
• What is meant by atomic size? Write its unit.
• What are the salient features of Rutherford’s atomic model?
• How Rutherford discovered that atom has a nucleus located at the centre of the atom?
• What are the defects of Rutherford atomic model?
• Give two postulates of Bohr’s atomic theory.
• How it is related to gram?
• What is the relative atomic mass?
• Find out the mass of 3 moles of oxygen atoms.
• Why the size of atom decreases in a period?
• How to atoms follow octet rule?
• What is trend of atomic radius in period and group?
• Calculate the number of atoms in 10 grams of Aluminum (Al).
• Differentiate between Homo atomic and Hetero atomic molecules.
• How is periodicity of properties dependent upon number of protons in an atom?
• Calculate the number of moles, number of molecule atoms present in 6 grams of water.
• How was it proved that electrons are fundamental particles of an atom?
• Give basic postulates of Bohr’s atomic theory.
• Give the electronic configuration of carbon atom.

Questions # 8

• Give the physical properties of sodium and its uses.
• Write any two uses of sodium.
• Why does sodium make ionic bond with chlorine?
• Why does sodium forma chemical bound with chloride?
• Why magnesium is harder than sodium.

Questions # 9

• Write down two uses of calcium.
• Give physical properties of calcium and its uses.
• Why calcium is more electropositive tan to magnesium?
• Write the chemical formulae of Aluminium Sulphate and Calcium Phosphate.

Questions # 10

• Define and explain Charles’s Law of gasses.
• Whether the density of gases increases on cooling? Explain.
• Why are the densities of gases lower than that of liquids?
• Why the gases are compressible?
• Why noble gases are not reactive?
• Can you cool a gas by increasing it volume?

Questions # 11

• What is meant by volume / volume %?
• What do you mean by %-mass / mass?
• Give the example and formula of mass by volume percent.
• There are 3.01 x 1023 molecules of CO2 present in a container.
• Calculate the number of moles of coal in the given mass.
• Calculate the number of moles and its mass. You have a piece of coal (carbon) weighing 9.0 grams.
• How can you differentiate between molecular formula, formula mass and empirical formula?
• Calculate the number of moles of coal in the given mass.

Questions # 12

• Briefly describe its principle, purpose and procedure.
• Define electroplating.
• What are non-electrolytes, give example?
• How electroplating of tin on steel carried out?
• How electroplating of zinc is carried out?
• In electroplating of chromium, which salt is used as an electrolyte?
• Which solution is used as electrolyte in Nelson’s cell?
• Differentiate between strong and weak electrolytes.

Questions # 13

• Define Galvanic cell.
• What is salt bridge?
• How the half cells of galvanic cell are connected?
• What is the difference between anode and cathode?
• What happens to cathode in the galvanic cell?
• What is the function of salt bridge?
• Write two differences between electrolytic and galvanic cell.

Questions # 14

• What do you mean by groups and periods in the periodic table?
• What do you mean by periodic function?
• What are the Defects in Long Form of Periodic Table?
• Define electron affinity.
• Explain the trend of electron affinity in periodic table.
• Describe its trend in periodic table.
• What do you mean by shielding effect?
• Discuss the important features of modern periodic table.
• Explain its trends in periodic table.
• Describe its trend in the periodic table.
• What is the difference between Mendeleev’s periodic law and modern periodic law?
• What are Halogens? Describe the position of halogen in periodic table?

Questions # 15

• Explain the term oxidation on the basis, of electrons concept with an example.
• Define valiancy.
• Describe oxidation and reduction in term of loss or gain of electron.
• What is the oxidation number Carbon in Na2CO3?
• Calculate oxidation number of nitrogen in HNO3.
• What is reduction?
• Explain with an example. Describe the rules for assigning the oxidation state.
• Oxidation and reduction proceed simultaneously.
• What is difference between valiancy and oxidation state?
• Explain the term oxidation on the basis of electronic concept with an example.

Questions # 16

• Write down general electronic configuration of carbon family.
• Write down the electronic configuration of chloride ion.
• Write down the electronic configuration of Na.
• Write down electronic configuration of chlorine.
• Write down the electronic configuration of Be and Ne.

Questions # 17

• What is the maximum capacity of a shell?
• Differentiate between shell and subshell.

Questions # 18

• A solution contains 50 g of sugar dissolved in 450 g of water.
• What is the unit of concentration?
• What is concentration of this solution?

Questions # 19

• What is meant by carbon dating?
• What is mole? Calculate the number of moles In 84 gram carbon.

Questions # 20

• Define chemical bond.
• What is meant by metric bond?
• Differentiate between lone pair and bond pair of electrons.
• Differentiate between Polar and non polar covalent bond.
• Describe at least two necessary conditions for the formation of a covalent bond.
• How coordinate covalent bond is formed in the hydronium ion?
• What is the cause of polarity in covalent bond?
• What type of covalent bond is formed in nitrogen molecule?
• Why have water polar covalent bonds?
• Define ionic bond, explain different steps in the formation of NaCr.
• What is a triple covalent bond, explain with an example?
• What is a coordinate covalent bond? Explain it with example.
• What is metallic bond? Explain the metallic bonding with the help of a diagram.
• Explain double covalent bond with the help of an example.
• Define hydrogen bonding. Explain how these properties affect the physical properties of compound.
• Define ionic bond and Why ionic compounds are easily soluble in water?
• Define coordinate covalent bond. How it is formed. Explain with examples.

Questions # 21

• Differentiate between Oxidizing agents and Reducing agents with the help of an example.
• Define reducing agent.

Questions # 22

• Which form of sculpture exists at room temperature?
• Define transition temperature.
• What is absolute temperature?
• What is general principle of solubility?
• What is absolute zero temperature?
• What is the effect of temperature on solubility?
• Define pressure and write its unit.
• What is vapor pressure and how it is affected by intermolecular forces?
• Why is vapour pressure higher at high temperature?
• Define atmospheric pressure.

Questions # 23

• Briefly describe the electrolysis of water.
• What is electrolysis?
• Describe the process that take place in the electrolysis of molten NaCI.

Questions # 24

• How can distinguish between solution and pure solvent?
• How you can explain the solute-solvent interaction to prepare a NaCl solution?
• Define solute and solvent.
• Differentiate between solute and solvent with examples of each.

Questions # 25

• Define aqueous solution.
• What does mean by unsaturated solution?
• Define super saturated solution When we dissolve 20 g of NaC1 in 400 cm3 of solution, what will be its molarity?
• What is molarity and give its formula to prepare molar solution?
• How much NaOH is required to prepare 500cm3 of 0.4M solution?
• What is the major difference between a solution and a mixture?
• Describe different ways of expressing the percentage composition of a solution.
• Describe Nelson’s Cell for the manufacture of Caustic soda from brine solution.
• What is meant by Molar Solution? How it is prepared.
• Compare the characteristics of solution, colloid and suspension.
• Why a solution is considered mixture?
• Differentiate between dilute solution and concentrated solutions with a common example.
• Why the alloys are considered solutions?

Questions # 26

• Define electron electivity.
• Define electro chemistry.
• How electro negativity does differ from electron affinity?
• What is electro negativity?
• What is the relationship between electro positively and ionization energy?
• What is relationship between electro negativity and polarity?
• Describe the trends of electro negativity in a period and in a group.

Questions # 27

• Why chlorine can accept only 1 electron?
• When does an electron emit or absorb energy?

Questions # 28

• What are synthetic adhesives?
• What you know about Epoxy adhesives?

Questions # 29

• Write any five characteristics of mixture.
• What is meant by mixture?
• State the reason soft drink is a mixture and water is a compound.
• Why does ice float on water?
• Find out the molecules in 9 gram of water.
• State any three difference between compound and mixture.
• How does homogeneous mixture differ from heterogeneous mixture?
• State three reasons why do you think air is a mixture and water a compound.
• Why does not the suspension form homogeneous mixture?

Questions # 30

• Describe the phenomenon of diffusion in liquids along the factors which influence it.
• Define diffusion.
• What is difference between diffusion and effusion?
• Describe the factors which influence the diffusion of liquid.

Questions # 31

• Write the name of factors which effect evaporation.
• Define evaporation.
• What do you mean by evaporation, how it is affected by surface area?
• What is difference between boiling point and evaporation?
• What is the relationship between evaporation and boiling point of liquid?
• Evaporation causes cooling. Explain.

Questions # 32

• What did you mean by the Thermal conductivity of the metallic compounds?
• What do you mean by metallic character?

Questions # 33

• How can a non-spontaneous reaction be carried out in an electrolytic cell? Discuss in detail.
• What are spontaneous and non spontaneous reactions?

Questions # 34

• Distinguish between amorphous solid and crystalline solid.
• Define crystalline solid and give its two examples.

Questions # 35

• What is difference between colloids and suspensions?
• How can you justify the milk is colloid?
• Why are the colloids quite stable?
• What is meant by colloid? Give two examples.

Questions # 36

• Why are liquids mobile?
• Write two properties of liquids.

Questions # 37

• Write four properties of covalent compounds.
• What are ionic and covalent compounds?
• Ionic compounds are solids justify.
• Write two properties of solids.

Questions # 38

• Give the trend of ionization energy in a period.
• Define Ionization energy.
• Why ionization energy Na is less than Mg?
• Why the ionization energy of Na more than K?
• What is second ionization energy and how is it represented?

Questions # 39

• What are radioactive isotopes?
• Write isotopes of chlorine.
• Give one example each of the use of radioactive isotope in medicine and radio therapy.
• Describe some major applications of radioactive isotopes in our surroundings.
• Write down any three isotopes of uranium.
• What is isotope? Discuss the structure of Isotope with suitable examples.
• Give the applications of isotopes in the field of radiotherapy and medicines.
• Describe the isotope of hydrogen with diagram.
• What is an isotope?

Questions # 40

• Write at least two physical properties of magnesium.
• What is meant by magnesium ribbon and where it use?
• Write down any two uses of magnesium.

Questions # 41

• Briefly describe the electrolytic refining of copper.
• What is electrolytic cell briefly describe its construction and working?
• Give the difference between electrolytic cell electro chemical cells.

Questions # 42

• What is inolarity? Write its formula.
• Describe the significance of chemical formula.

Questions # 43

• Write different types of molecules What is the difference molecule and molecular ion?
• What is a molecule?

Questions # 44

• Write a note on the construction of a Daniel Cell.
• Briefly describe the construction and working of Daniel cell?

Questions # 45

• Write any two chemical properties of halogens.
• Write down the important chemical reactions of halogens.

Questions # 46

• Why we stir paints thoroughly before using?
• Define substance. Mole is SI unit for the amount of a substance. Define it with examples.
• Define boiling point and also explain the factors which are affected on it?
• Explain classical theory of radiation
• Discuss the construction and working of a cell in which electricity is produced.
• Write a short note on Allotropy.
• Describe the classification of Dobereiner’s triads and give one example.
• What do you mean by cation and anion? Explain with examples.
• What are redox reactions?
• Give chemical reaction between methane (CH4) and chlorine (Ct2 ) in the presence of diffused light.
• Write the names of Electro chemical cells.
• Complete and balance the given chemical equation Na+H2
• Define analytical chemistry.
• Differentiate between periods and groups.
• Define empirical forthula with example.
• What is Metalloid?
• What is matter?
• Ionic compounds form solids. Justify.
• What do you mean by dynamic equilibrium?
• What do you mean by Pascal? How many Pascals are equal to I atm.
• What do you mean by solubility?
• What is meant by density?
• What is suspension?
• What is meant by condensation?
• What is meant by Brine?
• What is meant by chemical reactivity?
• What is Lewi’s Structure Diagram?
• What is % v/m ?
• What is electro positivity? Explain with an example.
• Define industrial chemistry.
• Define bio chemistry and give the scope of bio chemistry.
• Define physical chemistry.
• How can you differentiate between organic and inorganic chemistry?
• For what purpose is u-235 used?
• Explain ductile.
• Give experimental verification of Charles’s law.
• Define oxidizing agent.
• Define quantum theory.
• Define symbol and valency with example. What is meant by variable valency?
• Define homoatomic and hetroatomic morecule with examples.
• Define freezing point.
• Define malleable.
• Define effective nuclear charge.
• Define morality and writes its unit.
• Define nuclear fission reaction
• A patient has goiter. How will it be detected?
• Define Nuclear Chemistry.
• What is the difference between ions and free radicals?
• Write the definition of Duplet rule and Octet role.
• What is the nature of electrode used in electrolyzing of chromium?
• What is meant by periodicity of properties?
• What is difference between steel and stainless steel?
• Define Alkali metals and Alkaline earth metals.
• What is Dielectric Constant?
• What are intermolecular forces?
• Explain the term absolute zero.
• Name the by-products produced in Down’s cell.
• Why an iron grill is pointed frequently?
• How can you prove that angular momentum is quantized?
• Why is HF a weak acid?
• Why do you mean by malleability?

 

The complexity of a midlife crisis compared to adolescence is that successful people are often not ready:

learn a new mental skill (to develop the intellect is not the same thing as to develop an applied skill. This will require more attention and time);
take on intellectual work that pays worse than simple and understandable work;
to update the social environment, including by lining up in intellectual communities.
NEGATIVE UTILITY OF LABOR
Why do people often prefer to relax rather than work? One explanation is the principle of the negative utility of labor, according to which people prefer leisure to work. Other things being equal, a person would prefer leisure than work or study. Economists believe that people engage in work only because it indirectly brings more benefits than leisure. That is, in the future, a person may satisfy preferences that rank higher than current preferences.

Thus, we adopt the main property of leisure for work and study. When it is possible to work or study in the stream, then they often talk about their favorite work or the desire to study.