HSC Science (Electronics) 12th Standard Board Exam - Maharashtra State Board Question Bank Solutions for Chemistry

What are racemates?

Answer the following in one or two sentences.

Which of the three types of packing used by metals makes the most efficient use of space and which makes the least efficient use?

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Mention two properties that are common to both hcp and ccp lattices.

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Calculate the packing efficiency of metal crystal that has simple cubic structure.

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Cesium chloride crystallizes in a cubic unit cell with Cl^– ions at the corners and a Cs⁺ ion in the center of the cube. How many CsCl molecules are there in the unit cell?

Cu crystallizes in fcc unit cell with edge length of 495 pm. What is the radius of Cu atom?

The density of iridium is 22.4 g/cm³. The unit cell of iridium is fcc. Calculate the radius of iridium atom. Molar mass of iridium is 192.2 g/mol.

Aluminium crystallizes in a cubic close-packed structure with a unit cell edge length of 353.6 pm. What is the radius of Al atom? How many unit cells are there in 1.00 cm³ of Al? 

In ionic crystalline solid atoms of element Y form hcp lattice. The atoms of element X occupy one-third of tetrahedral voids. What is the formula of the compound?

An element has a bcc structure with a unit cell edge length of 288 pm. How many unit cells and a number of atoms are present in 200 g of the element? (1.16 × 10²⁴, 2.32 × 10²⁴)

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Pressure cooker reduces cooking time for food because _______.

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How vapour pressure lowering is related to a rise in the boiling point of solution?

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Why vapour pressure of a solvent is lowered by dissolving a nonvolatile solute into it?

Answer the following in one sentence :

Why is KCl solution neutral to litmus?

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Why is it necessary to add H₂SO₄ while preparing the solution of CuSO₄?

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The aqueous solution of sodium carbonate is alkaline whereas the aqueous solution of ammonium chloride is acidic. Explain.

What is meant by hydrolysis?

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A solution of CH₃COONH₄ is neutral. why?

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The standard potential of the cell in which the following reaction occurs:
H₂ (g,1 atm) + Cu²⁺ (1M) → 2H⁺ (1M) + Cu_(s),
`("E"_"Cu"^circ = 0.34 "V")` is

Consider the half reactions with standard potentials.

1. \[\ce{Ag^{\oplus}_{ (aq)} + e^{\ominus} -> Ag_{(s)}E^\circ = 0.8 V}\] 
2. \[\ce{I2_{(s)} + 2e^\ominus -> 2I^{\ominus}_{(aq)} E^\circ = 0.53V}\]
3. \[\ce{Pb^{2\oplus}_{(aq)} + 2e^{\ominus} -> Pb_{(s)} E^\circ = -0.13 V}\]
4. \[\ce{Fe^{2\oplus} + 2e^{\ominus} -> Fe_{(s)} E^\circ = -0.44 V}\]

The strongest oxidising  and reducing agents respectively are ______.