Description : Why is sodium metal kept under kerosene oil ?
Last Answer : Ans. Sodium metal is highly reactive and combines with air forming sodium oxide.
Description : Why is sodium preserved in kerosene?
Last Answer : Sodium is highly reactive in air. It reacts with air gradually forming sodium carbonate. It catches fire and burns when exposed to air. It does not react with kerosene so sodium is preserved in kerosene.
Description : If I am coloured, I smell, if I am burned, I smell, orange and yellow will melt me. What am I? -Riddles
Last Answer : A Candle.
Description : In cold countries alcohol is preferred to mercury as a thermometric liquid because (a) alcohol is a better conductor of heat (b) alcohol can be coloured and its level seen easily (c) alcohol has a lower freezing point than mercury (d) alcohol is cheaper than mercury
Last Answer : Ans:(c)
Description : Why does ice coverfed in sawdust ct melt quickly? (1) Sawdust does not allow the air to touch the ice (2) The water is absorbed by sawdust (3) Sawdust is a bad conductor of heat (4) Sawdust is good conductor of heat
Last Answer : (3) Sawdust is a bad conductor of heat Explanation: Ice needs to absorb heat energy to melt and become water (called latent heat of fusion). Since saw-dust is a poor conductor of heat, it takes ... required heat energy. This allows ice to remain in solid state for more time when packed in saw dust.
Description : Why does ice covered in sawdust not melt quickly ? (1) Sawdust does not allow the air to touch the ice (2) The water is absorbed by sawdust (3) Sawdust is a bad conductor of heat (4) Sawdust is good conductor of heat
Last Answer : Sawdust is a bad conductor of heat
Description : Light coloured clothes are preferred in summer because (a) light colours are good radiators of heat (b) light colours are poor absorbers of heat (c) they soak sweat faster (d) they allow body heat to escape faster
Last Answer : Ans:(b)
Description : 10.(a) An ore on treatment with dilute hydrochloric acid produces brisk effervesces. What type of ore is this? What steps will be required to obtain metal from the enriched ore. , (b) ... in coin and colour of the solution ? Write balanced chemical equation of the reaction involved. -Chemistry
Last Answer : (a) Carbonate ore: (i) Calcination: Carbonate ore is heated in limited supply of air and oxide is obtained, e.g. (b) Copper, being more reactive than silver will displace silver from silver nitrate ... and there will be deposition of silver on copper coin. The colour of solution will turn to blue.
Description : Which of the following is very reactive and kept in kerosene? (1) Sodium (2) Potassium (3) Iodine (4) Bromine
Last Answer : (1) Sodium Explanation: Sodium is a very reactive metal. It reacts vigorously with oxygen and water. A lot of heat is generated in this process. Therefore, it is stored in kerosene to avoid contacts between either atmospheric oxygen or water.
Description : White phosphorus is generally kept under – (1) Alcohol (2) Water (3) Glycerine (4) Kerosene oil
Last Answer : (2) Water Explanation: White phosphorous is kept under water because it reacts with oxygen but not water. Besides, it is insoluble in water. It presents a significant fire hazard due to its extreme reactivity with atmospheric oxygen.
Description : White phosphorus is always kept under (1) benzene (2) kerosene (3) ether (4) water
Last Answer : (4) water Explanation: White phosphorus is a material made from a common allotrope of the chemical element phosphorus that is used in smoke, tracer, illumination and incendiary munitions. Other common names include WP ... on fire, and cause serious burns or death and that is why it is kept in water.
Last Answer : Sodium
Description : White phosphorus is generally kept under (1) Alcohol (2) Water (3) Glycerine (4) Kerosene oil
Last Answer : Water
Last Answer : water
Description : Woollen cloth protects the body from cold because – (1) it is a good conductor of heat (2) it is a poor conductor of heat (3) external heat rays enter into the body through the woollen cloth (4) it reflects heat
Last Answer : (2) it is a poor conductor of heat Explanation: It is just because woolen clothes have fibres and between those fibres air is trapped which reduces heat loss. It reduces heat loss because it is an insulator or poor conductor of heat.
Description : Match the items given in column I with those in column II and select the correct option given below. Column I Column II A. Herbarium (i) It is a place having a collection of preserved plants and animals. B. Key (ii) A list that ... ii) (i) (iv) (c) (ii) (iv) (iii) (i) (d) (iii) (iv) (i) (ii)
Last Answer : (d) (iii) (iv) (i) (ii)
Description : The National Educational Policy of 1979, recommended also about the public schools Options: A) their uniquencies and traditions have to preserved the interests of the best talents of the country B) they ... D) suitable ratio has to be maintained for admission of middle class and poor student also.
Last Answer : D) suitable ratio has to be maintained for admission of middle class and poor student also.
Description : Tightly knit metal braid wire can be used with a printed circuit board when ___________. A. conductor flexibility is required B. desoldering components in the circuit C. electrically produced magnetic ... cause inaccuracies in adjacent components D. reactance in the circuit must be kept to a minimum
Last Answer : Answer: B
Description : A few normal seedlings of tomato were kept in a dark room. After a few days they were found to have become white-coloured like albinos. Which of the following terms will you use to describe them? (a) Mutated (b) Embolised (c) Etiolated (d) Defoliated
Last Answer : (c) Etiolated
Description : Will the Lustrous Henna All Natural Hair Dye wash out?
Last Answer : The Lustrous Henna hair dye will wash out, but it will take several rinses for it to wash away completely.
Description : How long does the Lustrous Henna All Natural Hair Dye last?
Last Answer : The Lustrous Henna hair dye will last for probably five or six rinses before it washes away, so it depends on how often you shower.
Description : A material is called 'ductile', if it can be (A) Drawn into wires (B) Hammered to a thin sheet (C) Fractured without deformation (D) Made lustrous by heating it
Last Answer : (A) Drawn into wires
Description : Which of the following petrological constitutes is responsible for bright and lustrous black band of bituminous coal? (A) Vitrain (B) Clarain (C) Durain
Last Answer : (A) Vitrain
Description : What changes will happen to a bowl of ice and water kept at exactly zero degree Celsius? (1) All ice will melt (2) All water will become ice (3) No change will happen (4) Only some ice will melt
Last Answer : (3) No change will happen Explanation: Fresh water cooled to zero (0) degree Celsius and subjected to additional loss of heat energy normally will freeze. A mixture of fresh water and ice ... the usual freezing point while remaining liquid. Such cloud droplets are composed of super cooled water.
Description : Melt spinning of polymers involves the forcing of polymer melt through spinnerates (fine holes) into an atmosphere kept at a temperature lower than the melting point of the polymer, which causes the fine diameter ... the __________ fibres. (A) Acrylic (B) Polyester (C) Nylon 6:6 (D) Polypropylene
Last Answer : (A) Acrylic
Description : What changes will happen to a bowl of ice and water kept at exactly zero degree Celsius ? (1) All ice will melt (2) All water will become ice (3) No change will happen (4) Only some ice will melt
Last Answer : No change will happen
Description : Solid type cables are considered unreliable beyond 66 kV because (a) insulation may melt due to higher temperature (b) skin effect dominates on the conductor (c) of corona loss between conductor and sheath material (d) there is a danger of breakdown of insulation due to the presence of voids
Last Answer : (d) there is a danger of breakdown of insulation due to the presence of voids
Description : In the case of peppered moth (Biston betularia) the black-coloured form became dominant over the light-coloured form in England during industrial revolution. This is an example of (a) ... acquired due to the darker environment (d) natural selection whereby the darker forms were selected.
Last Answer : (d) natural selection whereby the darker forms were selected.
Description : Explain the following , giving reason . (a) Transition metal and many of their compounds show paramagnetic behavior (b) The enthalpy of atomisation of the transition metal is high . (c) The Transition metal generally form coloured compounds .
Last Answer : Ans(a) It is due to unpaired electrons . (b) It is due to strong metallic bond and additional Covalent bonds due to presence of unpaired electron in d- orbitals (c) It is due to presence of unpaired electrons ,they undergo d-d transition .
Description : Which are the two metals kept in kerosene?
Last Answer : Sodium; Potassium
Description : Potassium is kept & transported under (A) Water (B) Liquid ammonia (C) Kerosene oil (D) Alcohol
Last Answer : (C) Kerosene oil
Description : 1. Funds belonging to the Government of India are kept in which fund? 2. Why does Kerosene oil rise up in the wick of lantern? 3. Where is the headquarters of Food and Agriculture Organisation? ... 19. Which feature is the product of vulcanicity? 20. From where was the term Congress' derived?
Last Answer : Answer : 1 1. Consolidated Fund of India 2. Because of surface tension 3. Rome 4. Low moisture 5. Greeks 6. Income 7. Calcium and iron 8. Habeas Corpus 9. Equator 10. Spinning wheel 11. Na2 CO3 12. ... a type of garment 16. Brain 17. 24 18. Less than 90° 19. Caldera 20. The History of North America
Description : Is kerosene conductor or insulator?
Last Answer : its an insulator
Description : Good conductor of electricity is – (1) dry air (2) paper (3) kerosene (4) graphite
Last Answer : (4) graphite Explanation: Graphite has a tendency to behave very much like a metal because the carbon molecules arrange themselves into a lattice structure. The crystal lattice is the same orientation that ... better than the dry air paper and kerosene and that's what makes it a good conductor.
Description : Good conductor of electricity is (1) dry air (2) paper (3) kerosene (4) graphite
Last Answer : graphite
Description : Why is it a poor practice to use a high wattage soldering iron when soldering or desoldering components on a printed circuit board? A. The circuit board will blister and warp. B. The foil wire bonded ... board has a low melting temperature. D. The solder is kept to a dull heat dissipating finish.
Description : Ice is packed in saw dust because – (1) saw dust will not get melted easily. (2) saw dust is poor conductor of heat. (3) saw dust is a good conductor of heat. (4) saw dust does not stick to the ice.
Last Answer : (2) saw dust is poor conductor of heat. Explanation: ice needs to absorb heat energy to melt and become water (called latent heat of fusion). Since saw-dust is a poor conductor of heat, it takes ... required heat energy. This allows ice to remain in solid state for more time when packed in saw dust.
Description : Outside of cooking utensils are generally left black from below because – (1) it is difficult to clean daily. (2) black surface is a good conductor of heat. (3) black surface is a poor conductor of heat. (4) black surface is a good absorber of heat.
Last Answer : (4) black surface is a good absorber of heat. Explanation: The outside surface of a utensil used for heating is coated black so that it may absorb more heat and make heating quicker. This is because black surface is a good absorber of heat.
Description : Ice is packed in saw dust because (1) saw dust will not get melted easily. (2) saw dust is poor conductor of heat. (3) saw dust is a good conductor of heat. (4) saw dust does not stick to the ice.
Last Answer : saw dust is poor conductor of heat.
Description : Outside of cooking utensils are generally left black from below because (1) it is difficult to clean daily. (2) black surface is a good conductor of heat. (3) black surface is a poor conductor of heat. (4) black surface is a good absorber of heat.
Last Answer : black surface is a good absorber of heat.
Description : Woollen cloth protects the body from cold because (1) it is a good conductor of heat (2) it is a poor conductor of heat (3) external heat rays enter into the body through the woollen cloth (4) it reflects heat
Last Answer : it is a poor conductor of heat
Description : Metal tea pots have wooden handles because – (1) wood is a bad conductor of heat (2) it prevents electric shock (3) it gives beauty to the pots (4) it is hygienic
Last Answer : (2) it prevents electric shock Explanation: Wood is a bad conductor of heat due to the arrangement of its molecules. As the molecules of wood are far from each other, they cannot pass heat through them.
Description : You are provided with magnesium ribbon and sulpher powder. Explain with the help of an activity that metal oxides are basic and non-metal oxide are acidic in nature. -Chemistry
Last Answer : Aim: To test the nature of oxides formed by metals and non-metals. Materials Required: Sulphur powder, Mg ribbon, water, blue litmus paper, red litmus paper. Procedure: 1.Take magnesium ribbon ... the metallic oxides are basic in nature whereas most of the non-metallic oxides are acidic in nature.
Description : The snow on the mountains does NOT melt all at once when it is heated by the sum because: (1) It becomes very hard (2) It reflects most of the heat from the sum (3) it has a low specific heat capacity (4) it has a high latent heat of fusion
Last Answer : (2) It reflects most of the heat from the sum Explanation: Newly formed snow reflects about 90 per cent of the sunlight that falls upon it. This means that the sun is powerless to melt clean snow. And when ... on a spring day because of the sun's heat. It melts because of the warm air from the sea.
Description : The energy required to melt one mole of a solid at its melting point is called one of the following. w) the molar heat of fusion x) the molar hear of vaporization y) the molar heat of capacity z) the melting point
Last Answer : ANSWER: W -- THE MOLAR HEAT OF FUSION
Description : Which one of the following non-metals is not a poor conductor of electricity? (1) Sulphur (2) Selenium (3) Bromine (4) Phosphorus
Last Answer : (2) Selenium Explanation: Selenium is a non-metallic element; it is not a very good conductor of heat and electricity.
Description : Give reason for the following observation (L-III) (a)- The tendency for catenation decreases down the group in group 14 (b)- The decreasing stability of+3 oxidation state with increasing atomic no. in group 13. (c)- Molten aluminum bromide is a poor conductor of electricity.
Last Answer : Ans. -(a) it is due to decrease in bond dissociation energy which is due to increase in atomic size C-C > Si-Si >Ge-Ge>Sn-Sn>Pb-Pb. (b)- It is due to inert pair effect. (c)- Molten AlBr3 is poor conductor of electricity because it is covalent compound.
Description : Can broccoli or cauliflower be canned/heat preserved?
Last Answer : As far as I know, it cannot. But due to prior knowledge I have also seen people do crazy things with vegetables and fruits, so canning might be a possibility, they aren’t very sturdy though, I think that is why manufacturers deter from them.