Which of the following metals is used in the thermite welding process?
A. Lead
B. Copper
C. Zinc
D. Aluminium
Answer: Option D
Solution (By JKSSB Mock Tests)
Thermite: Fe₂O₃ + 2Al → 2Fe + Al₂O₃. Aluminium powder reduces iron oxide, producing molten iron for welding. Al is chosen due to its high reactivity and exothermic reaction.
Explanation:
Boron trifluoride (BF₃) has covalent bonds where boron shares three electrons with three fluorine atoms. Although BF₃ can accept a lone pair to form coordinate bonds (as in BF₄⁻), its own bonds are polar covalent. Ionic bonding occurs between metal and non-metal.
Explanation:
An alpha particle (α) consists of 2 protons and 2 neutrons, which is the same as a helium-4 nucleus (²⁴He²⁺). It has a +2 charge. Beta particles are electrons (β⁻) or positrons (β⁺). Gamma rays are electromagnetic waves with no mass or charge. Alpha particles have low penetration power and are stopped by a sheet of paper or skin. Rutherford used alpha particles in his scattering experiment.
Explanation:
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.
No comments yet. Be the first to start the discussion!