What is the hybridisation of [PtCl4]2- and how?
Answer: Redistribution of the energy of orbitals of individual atoms to give orbitals of equivalent energy happens when two atomic... View Article
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Give examples for eurythermal and stenothermal organisms.
Answer: Eurythermal organisms are those which can tolerate a wide range of temperatures. Examples: Cow Human Monkey Goats Sheep Stenothermal... View Article
What is the mass of 10 moles of sodium sulphite (Na2S04)?
Answer: A mole is defined as the mass of the substance which consists of the equal quantity of basic units.... View Article
What is OPV?
Answer: The IPV stands for inactivated polio vaccine and the OPV stands for oral polio vaccine are the vaccines available... View Article
Solve by factorization method: (4/x ) -3 = 5/ (2x + 3) , x≠ 0, -3/2.
Answer: Given expression is \(\begin{array}{l}\left ( \frac{4}{x} \right )- 3 = \frac{5}{2x + 3}\end{array} \) Solve the above expression \(\begin{array}{l}\frac{4... View Article
An AP consists of 37 terms. The sum of the three middlemost terms is 225 and the sum of the last three is 429. Find the AP.
Answer: We know that, First term of an AP = a Common difference of AP = d nth term of... View Article
Why is the dipole moment of benzene zero?
Answer: In any system in which there is a charge separation, a dipole moment occurs. It occurs in both ionic... View Article
What happens when sodium carbonate reacts with hydrochloric acid?
Answer: When dilute hydrochloric acid reacts with sodium carbonate, then sodium chloride, carbon dioxide and water are formed. A brisk... View Article
What is the chemical name and formula of sindoor?
Answer: Pb3O4 Red lead that is produced from cinnabar is vermilion or sindoor. These cinnabar blocks are generally crushed and... View Article
Find the zeros of the following quadratic polynomials and verify the relationship between the zeros and the coefficients. 4s2 − 4s + 1.
Answer: Polynomials are algebraic expressions that consist of variables and coefficients. Variables are also sometimes called indeterminates. Polynomial is defined as... View Article
An element X on exposure to moist air turns reddish-brown and a new compound Y is formed. The substance X and Y are (1) X = Fe, Y = Fe2O3 (2) X = Ag, Y = Ag2S (3) X = Cu, Y = CuO (4) X = Al, Y = Al2O3
Answer: (1) X = Fe, Y = Fe2O3 The exposure of element X to moist air forms a reddish brown... View Article
On immersing an iron nail in CuSO4 solution for a few minutes, you will observe (1) No reaction takes place (2) The colour of solution fades away (3) The surface of iron nails acquire a black coating (4) The colour of solution changes to green
Answer: (4) The colour of the solution changes to green We will observe a shift of colour from blue to... View Article
The reaction in which two compounds exchange their ions to form two new compounds is called (1) Displacement reaction (2) Combination reaction (3) Double displacement reaction (4) redox reaction
Answer: (3) Double displacement reaction When a component of two ionic compounds is exchanged and two new components are made,... View Article
Rancidity can be prevented by (1) Adding antioxidants (2) Storing food away from light (3) Keeping food in the refrigerator (4) All of these.
Answer: (4) All of these Rancidity is a very particular term that refers in the most general way to the... View Article
In which of the following, heat energy will be evolved? (1) Electrolysis of water (2) Dissolution of NH4Cl in water (3) Burning of L.P.G. (4) Decomposition of AgBr in the presence of sunlight
Answer: (3) Burning of L.P.G. Fuels release heat on burning. Heat of combustion is total amount of heat released when... View Article
When a magnesium ribbon is burnt in air, the ash formed is (1) Black (2) White (3) Yellow (4) Pink
Answer: (2) White When magnesium ribbon is burnt in air, it combines with oxygen to form white powder magnesium oxide... View Article
Dilute hydrochloric acid is added to granulated zinc taken in a test tube. The following observations are recorded. Point out the correct observation. (a) The surface of metal becomes shining (b) The reaction mixture turns milky (c) Odour of a pungent-smelling gas is recorded (d) A colourless and odourless gas is evolved.
Answer: (d) A colourless and odourless gas is evolved. A colourless and odourless gas is produced with bubbles when diluting... View Article
Why do fireflies glow at night?
Answer: Inside their bodies, fireflies create a chemical reaction that causes them to emit light. This kind of light emission... View Article
When crystals of lead nitrate are heated strongly in a dry test tube (1) Crystals immediately melt (2) Brown residue is left (3) White fumes appear in the tube (4) Yellow residue is left
Answer: (4) Yellow residue is left The evolution of brown gas, nitrogen dioxide, and a yellow residue of lead oxide... View Article
A silver article turns black when kept in the open for a few days due to the formation of (1) H2S (2) AgS (3) AgSO4 (4) Ag2S
Answer: (4) Ag2S When placed in the air, the silver object turns black because the silver element reacts with sulphur... View Article
