MDCAT ECAT Chemistry MCQs with Answers – All Units – Page 6

Question 101 s- and p-Block Elements

Why does nitrogen have a higher first ionisation energy than oxygen?

Correct answer B. Nitrogen has a stable half-filled 2p subshell

Open question

Question 102 s- and p-Block Elements

Which element has the highest electronegativity on the Pauling scale?

Correct answer B. Fluorine

Open question

Question 103 s- and p-Block Elements

Chlorine releases more energy than fluorine on gaining an electron mainly because ____.

Correct answer B. the small 2p shell of fluorine causes strong electron repulsion

Open question

Question 104 s- and p-Block Elements

An element whose last electron enters a 4f subshell belongs to which block of the periodic table?

Correct answer B. f-block

Open question

Question 105 s- and p-Block Elements

Which metal mainly forms a superoxide when burnt in excess oxygen?

Correct answer C. Potassium

Open question

Question 106 s- and p-Block Elements

Which Group II element does not react with water even when heated?

Correct answer D. Beryllium

Open question

Question 107 s- and p-Block Elements

Magnesium reacts with steam to produce ____.

Correct answer B. magnesium oxide and hydrogen

Open question

Question 108 s- and p-Block Elements

Which Group IV element shows the most stable +2 oxidation state?

Correct answer D. Lead

Open question

Question 109 s- and p-Block Elements

How many grams of hydrogen gas are produced when 4.6 g of sodium reacts completely with water (Na = 23, H = 1)?

Correct answer D. 0.2 g

Open question

Question 110 s- and p-Block Elements

What volume of hydrogen at STP is released when 2.4 g of magnesium reacts completely with steam (Mg = 24)?

Correct answer D. 2.24 dm³

Open question

Question 111 s- and p-Block Elements

What mass of calcium chloride forms when 4.0 g of calcium burns completely in chlorine (Ca = 40, Cl = 35.5)?

Correct answer C. 11.1 g

Open question

Question 112 Transition Elements

When a first-row transition metal atom forms a positive ion, electrons are removed first from the ____.

Correct answer D. 4s orbital

Open question

Question 113 Transition Elements

How many unpaired electrons are present in the Fe³⁺ ion?

Correct answer B. 5

Open question

Question 114 Transition Elements

How many unpaired electrons does the Cr³⁺ ion contain?

Correct answer D. 3

Open question

Question 115 Transition Elements

Which of these ions has the largest number of unpaired electrons?

Correct answer B. Mn²⁺

Open question

Question 116 Transition Elements

What is the spin-only magnetic moment of the Fe²⁺ ion?

Correct answer D. 4.90 BM

Open question

Question 117 Transition Elements

Zinc is not regarded as a typical transition element because ____.

Correct answer C. its atom and its Zn²⁺ ion both have a completely filled 3d subshell

Open question

Question 118 Transition Elements

Which of these ions is expected to be colourless in aqueous solution?

Correct answer C. Sc³⁺

Open question

Question 119 Transition Elements

What is the general outer electronic configuration of d-block elements?

Correct answer B. (n−1)d¹⁻¹⁰ ns¹⁻²

Open question

Question 120 Transition Elements

What is the oxidation state of chromium in potassium dichromate, K₂Cr₂O₇?

Correct answer D. +6

Open question