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- Question
Which one of the following elements is used as a timekeeper in atomic clocks?
Options- A. Potassium
- B. Caesium
- C. Calcium
- D. Magnesium
- Correct Answer
- Caesium
ExplanationWhen exposed to certain frequencies of radiation, such as radio waves, the subatomic particles called electrons that orbit an atom's nucleus will "jump" back and forth between energy states. Clocks based on this jumping within atoms can therefore provide an extremely precise way to count seconds.It is no surprise then that the international standard for the length of one second is based on atoms. Since 1967, the official definition of a second is 9,192,631,770 cycles of the radiation that gets an atom of the element called caesium to vibrate between two energy states.
- 1. Which of the following is a commercial source of energy?
Options- A. Agricultural waste
- B. Dried dung
- C. Sun
- D. Natural gas Discuss
- 2. When Granite rocks get metamorphosed, they form
Options- A. Quartzite
- B. Gneiss
- C. Marble
- D. Slate Discuss
- 3. Besides CO2, the other green house gas is
Options- A. CH4
- B. N2
- C. Ar
- D. O2 Discuss
- 4. Process of gaining electrons is known as _____.
Options- A. oxidation
- B. reduction
- C. radiation
- D. both oxidation and reduction Discuss
- 5. Which one of the following statements regarding histone proteins is correct?
Options- A. Histones are proteins that are present in mitochondrial membrane
- B. Histones are proteins that are present in nucleus in association with DNA
- C. Histones are proteins associated with lipids in the cytosol
- D. Histones are proteins associated with carbohydrates in the cytosol Discuss
- 6. Which one of the following gases dissolves in water to give acidic solution?
Options- A. Carbon dioxide
- B. Oxygen
- C. Nitrogen
- D. Hydrogen Discuss
- 7. Consider the following chemical reaction : aFe2O3(s) + bCO(g) + cFe(s) + dCO2 In the balanced chemical equation of the above, which of the following will be the values of the coefficients a, b, c and d respectively?
Options- A. 3, 2, 3, 1
- B. 1, 3, 2, 3
- C. 2, 3, 3, 1
- D. 3, 3, 2, 1 Discuss
- 8. Why is argon gas used along with tungsten wire in an electric bulb?
Options- A. To increase the life of the bulb
- B. To reduce the consumption of electricity
- C. To make the emitted light colored
- D. To reduce the cost of the bulb Discuss
- 9. Which one of the following is the correct relation between the Kelvin temperature (T) and the Celsius temperature (fc)?
Options- A. These are two independent temperature scales
- B. T = tc
- C. T = tc - 273.15
- D. T = tc + 273.15 Discuss
- 10. Which one of the following is not a characteristic of a compound?
Options- A. Composition is variable.
- B. All particles of compound are of only one type.
- C. Particles of compound have two or more elements.
- D. Its constituents cannot be separated by simple physical methods. Discuss
Chemistry problems
Search Results
Correct Answer: Natural gas
Correct Answer: Gneiss
Correct Answer: CH4
Correct Answer: reduction
Correct Answer: Histones are proteins that are present in nucleus in association with DNA
Explanation:
Histones are highly alkaline proteins found in eukaryotic cell nucleusthat package and order the DNA into structural units called nucleosomes. They are the chief protein components of chromatin, acting as spools around which DNA winds, and playrole in gene regulation.
Correct Answer: Carbon dioxide
Explanation:
Carbon dioxide (CO2) gas dissolved in water can cause water to become acidic.The acidity of water from dissolved CO2 can be reduced by a base such as baking soda (sodium bicarbonate).
Correct Answer: 1, 3, 2, 3
Explanation:
Fe2O3 + 3CO = 2Fe + 3CO2
Hematite + Carbon Monoxide = Iron + Carbon Dioxide
In this reaction, the iron oxide is reduced to iron, and the carbon is oxidised to carbon dioxide.
Correct Answer: To increase the life of the bulb
Explanation:
Argon gas is used in fluorescent and incandescent light bulbs to stop the oxygen in the light bulbs from corroding the hot tungsten filament.
The use of argon in light bulbs prevents the evaporation of the tungsten filaments, which results in increased light bulb life.
Argon is also used to create an inert atmosphere for growing semiconductor crystals, arc welding and for processes that need protection from other kinds of atmospheric gases.
Correct Answer: T = tc + 273.15
Explanation:
Lord Kelvin, working in Scotland, developed the Kelvin scale in 1848. His scale uses molecular energy to define the extremes of hot and cold. Absolute zero, or 0 K, corresponds to the point at which molecular energy is at a minimum. The Kelvin scale is preferred in scientific work, although the Celsius scale is also commonly used. Temperatures measured on the Kelvin scale are reported simply as K, not °K.
T (in °C) + 273.15 = T (in K)
T (in K) ? 273.15 = T (in °C)
Correct Answer: All particles of compound are of only one type.
Explanation:
A mixture is made from different substances that are not chemically joined.Compound:
?Two or more elements combine together chemically to form a new substance called compound.
?The different elements are chemically joined together.?Compounds are homogeneous, i.e. their properties are the same throughout
?The compound has properties different from the elements it contains.
?It can only be separated into its elements using chemical reactions. (not using physical methods)
?During the formation of a compound from its elements, a certain amount of energy in the form of heat, light, electricity is either absorbed or evolved
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