Mendeleev predicted the existence of an element 'eka-silicon', later discovered and named:
A. Scandium
B. Gallium
C. Germanium
D. Arsenic
Answer: Option C
Solution (By JKExamLibrary)
Mendeleev left gaps and predicted properties of eka-boron (scandium), eka-aluminium (gallium), and eka-silicon (germanium). Germanium was discovered in 1886, its properties matched predictions, confirming the periodic law.
Explanation:
Detergents emulsify grease by forming micelles around oil droplets, removing them from fabric. Soap does same but less effective in hard water.
Explanation:
From Faraday's first law, m = ZQ, so Z = m/Q. SI unit is kg/C, but practical unit is g/C. It is the mass of substance liberated per unit charge.
Consider the following statements: 1. Galvanization involves coating iron with zinc. 2. Sacrificial protection uses a more reactive metal to protect iron. Which is/are correct?
Explanation:
Galvanization is the process of applying a protective zinc coating to iron to prevent rusting. Sacrificial protection (or cathodic protection) involves connecting iron to a more reactive metal (like magnesium or zinc). The more reactive metal oxidizes preferentially, sacrificing itself to protect the iron. Both statements are correct.
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