Periodic Trends — Set 2
Chemistry · आवर्ती प्रवृत्तियां · Questions 11–20 of 50
The law of octaves was proposed by which scientist?
Correct Answer: A. Newlands
John Newlands proposed the law of octaves in 1864. He observed that every eighth element had properties similar to the first. This law was primarily applicable only up to the element calcium.
Which block of the periodic table contains only metals?
Correct Answer: C. f-block
The f-block, consisting of Lanthanides and Actinides, contains only metallic elements. These are often called inner transition metals. Most actinides are radioactive and some are synthetic.
Which trend increases down a group in the periodic table?
Correct Answer: B. Atomic Radius
Atomic radius increases down a group because new electron shells are added. The increased distance from the nucleus reduces the pull on outer electrons. This makes the overall size of the atom larger.
Which element is the lightest metal in the periodic table?
Correct Answer: C. Lithium
Lithium is the lightest metal and the least dense solid element. It belongs to the alkali metal group. Because of its low density, it can even float on water.
Who is considered the father of the modern periodic table for organizing it by atomic weights?
Correct Answer: B. Dmitri Mendeleev
Dmitri Mendeleev is credited with creating the first widely recognized periodic table. He organized elements by atomic mass and left gaps for undiscovered elements. His predictions about those elements were later proven correct.
Which group contains the most unreactive elements?
Correct Answer: D. Group 18
Group 18 elements are the Noble Gases and are chemically inert. They have completely filled valence shells, making them very stable. Examples include Neon, Argon, and Xenon.
The diagonal relationship exists between elements of?
Correct Answer: D. Period 2 and 3
A diagonal relationship exists between certain elements of the second and third periods. For instance, Lithium and Magnesium show similar chemical properties. This is due to their similar charge-to-size ratios.
Which element was named 'Eka-aluminum' by Mendeleev before its discovery?
Correct Answer: D. Gallium
Gallium was predicted by Mendeleev as 'Eka-aluminum' due to its position in the table. When discovered in 1875, its properties matched his predictions perfectly. It is a metal that can melt in your hand.
What is the common valency of Group 2 elements?
Correct Answer: A. +2
Group 2 elements, the alkaline earth metals, have two valence electrons. They lose these two electrons to achieve a stable noble gas configuration. This results in a common valency of +2.
Which of the following elements is a liquid at room temperature?
Correct Answer: D. Mercury
Mercury is the only metal that remains liquid at standard room temperature. It is often used in thermometers because of its high coefficient of expansion. Its symbol Hg comes from the Greek word Hydrargyrum.