The value of the universal gas constant 'R' in SI units is:
A. 8.314 J/(mol·K)
B. 0.0821 L·atm/(mol·K)
C. 8.314 L·atm/(mol·K)
D. 1.987 cal/(mol·K)
Answer: Option A
Solution (By JKExamLibrary)
The universal gas constant R has different values depending on the units used. In SI units (Joules), R = 8.314 J/(mol·K). In L·atm, it is 0.0821 L·atm/(mol·K). Option D mixes SI and L·atm units incorrectly. The value of R is fundamental in thermodynamic calculations.
Explanation:
Froth flotation is used to concentrate sulfide ores. Galena (PbS) is a sulfide ore; it is wetted by oil (pine oil) and comes to the surface with froth, while gangue particles wetted by water settle down. Bauxite (Al₂O₃·2H₂O) is an oxide ore concentrated by leaching (Bayer's process). Magnetite (Fe₃O₄) is magnetic ore separated by magnetic separation. Carnallite (KCl·MgCl₂·6H₂O) is a halide ore.
Explanation:
Sulphuric acid (H₂SO₄) is known as the 'King of Chemicals' because of its extensive use in various industries, including fertilizers, dyes, detergents, and petroleum refining. Its production is often considered an indicator of a country's industrial strength and economic development.
Assertion (A): The first ionization energy of Nitrogen is higher than that of Oxygen. Reason (R): Nitrogen has a half-filled p-orbital which is exceptionally stable.
A.Both A and R are true and R is the correct explanation of A.
B.A is false but R is true.
C.Both A and R are true but R is NOT the correct explanation of A.
Explanation:
Nitrogen (1s2 2s2 2p3) has a exactly half-filled p-subshell, which confers extra stability due to symmetry and exchange energy. Oxygen (1s2 2s2 2p4) has one paired electron in the p-orbital, leading to electron-electron repulsion, making it easier to remove. Thus, N has a higher IE than O. Both are true and R explains A.
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