Question

2. The element with atomic number 14 is hard and forms acidic oxide with a covalent
halide. To which of the following categories does the element belong?
(a) Metal
Metalloid
Non-metal
(d) left hand side element
3. Doberiener's system of classification into triad was not found to be useful as he
could identify only:
Two triads
(b) Three triads
(c) Four triads
(d) Five triads
4. The atomic number of an element is a more fundamental property than its atomic
mass was showed by:
(a) Henry Moseley
(b) J.Dobereiner
(c) John Newlands
(d) Mendeleev​

Answer 1

Explanation:

1. Silicon element
2. Explanation: Atomic number 14 is for Silicon element which is a metalloid and exhibit properties of both metals and non-metals. It has 4 electrons in its valence shell so tends to form covalent acidic oxide like non-metals.
3. Dobereiner could identify only three triads among the elements known at that time. Because of this Dobereiner's Classification of element was not found to be useful. ... After discovery of several new elements, their properties did not fit into the Law of Octaves.
4. Henry Moseley
5. The answer is Henry Moseley. The scientist who first of all showed that the atomic number is more fundamental property of an element than its atomic mass was Henry Moseley. He is best known for the Moseley's Law and contributions to Physics.

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