9th Class Chemistry Guess

 

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.

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