TEZPUR CLUSTER CLASS 10 SCIENCE SET 2

In the following reaction PbO+C---->Pb+CO which statement is correct?

• PbO is oxidised
• C acts as oxidising agent
• C acts as a reducing agent.
• Reaction doesn't represent redox reaction.

In autotrophic mode of nutrition organisms made there own food. In plants they absorb light energy. A green pigment present in leaves essential for absorption of light energy. Leaves are the parts of plants where plant construct there own food. During this process conversion of light energy to chemical energy takes place along splitting of water molecules into hydrogen and oxygen ( the gas which plants exhale during respiration) and reduction of carbon dioxide into carbohydrates. Which gas in photosynthesis process converts into carbohydrates?

• Carbon dioxide
• Oxygen
• Nitrogen
• Ozone

In which of the following, the identity of initial substance remains unchanged?

• Curdling of milk
• Formation of crystals by process of crystallisation
• Fermentation of grapes
• Digestion of food

Chemistry in Automobiles: For an internal combustion engine to move a vehicle down the road, it must convert the energy stored in the fuel into mechanical energy to drive the wheels. In your car, the distributor and battery provide this starting energy by creating an electrical "spark", which helps in combustion of fuels like gasoline. Below is the reaction depicting complete combustion of gasoline in full supply of air: 2C8H18 +25 O2------> 16 X + Y. which of the following are the products obtained from the reaction mentioned in the above case?

• a) X- CO2, Y- H2O2
• b) X- H2O, Y- CO
• c) X- CH3OH, Y- H2O
• d) X- CO2, Y- H2O

Ayush taken a silvery-white metal X in the form of ribbon, which Is when ignited, burns in air with a dazzling white flame to form a white powder Y. When water is added to powder Y, it dissolves partially to form another substance Z. What could metal X be and one day to day life use of compound Z is

• Metal X is Mg and compound Z used as Antacid to relieve indigestion
• Metal X is Cu and compound Z used as fungicides
• Metal X is Ca and compound Z used in white washing
• Metal X is Mg and compound Z is used to set fracture bones.

Which of these is a convex mirror?

• Shaving mirror
• Dentist’s mirror
• Headlight mirror of a bike
• Rear-view mirror of a car

A mirror magnify the image of an object by minus 1.5 times which of the following is true about the image produced by the mirror.

• Image is real, erect and larger than the object
• Image is real, inverted and larger than the object
• Image is virtual and larger than the object
• Image is virtual and smaller than the object

Which of the following is not a physical change?

• Dissolution of NaCl in water
• Melting of ice to give water
• Combustion of Compressed Natural Gas(CNG)
• Boiling of water to give water vapour

Take 5 ml of sodium sulphate solution in a test tube and 5 ml of barium chloride solution in another test tube. Mix the two solutions slowly and leave the test tube undisturbed for some time. A white precipitate is formed after some time. Which of the following statement is correct about the above reaction

• It is a double displacement reaction since exchange of ions occurs between two reactants.
• It is a combination reaction since barium ions combine with sulphate ions to give barium sulphate.
• It's a displacement reaction since chloride ions are replaced by sulphate ions.
• None of these

Which of the following statement is correct regarding the electrolysis of water?

• Oxidation takes place at the cathode.
• Reduction takes place at the cathode.
• Reduction takes place at the anode.
• Electrolysis is not a redox reaction.