Which of the following statements relating to the Modern Periodic Table is/are correct ? 1. The atomic radius increases on moving from left to right across a period. 2. Germanium, Tellurium, and Copper are transition metals. 3. The two isotopes of Chlorine occupy the same position in the periodic table. 4. The metallic property of Ca, Ba, Be and Sr follows the order : Be < Ca < Sr < Ba. Select the answer using the codes given below :
- A.3 only
- B.1 and 4
- C.2 and 3
- D.3 and 4
Correct answer
Explanation
The correct answer is D, 3 and 4. Only statements 3 and 4 are true; statements 1 and 2 are false.
The modern periodic table arranges elements by atomic number. Isotopes of an element have the same atomic number and differ only in neutrons, so Cl-35 and Cl-37 sit in the same box, which makes statement 3 true. Be, Ca, Sr and Ba all belong to group 2; metallic character rises down a group because the outer electron is farther from the nucleus and is lost more easily, so Be < Ca < Sr < Ba is right. Statement 1 is false: across a period the nuclear charge grows while electrons enter the same shell, so the atomic radius decreases. Statement 2 is false: germanium and tellurium are metalloids of the p-block; only copper is a transition metal.
A is wrong because it leaves out statement 4, which is also correct.
B is wrong because statement 1 is false.
C is wrong because statement 2 is false.
Exam tip: across a period radius falls and non-metallic character rises; down a group radius and metallic character both rise.
Practice Questions
View allConsider the following actions :
1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously
2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive
3. Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape mode
In how many of the above actions is the function of accelerometer required?
- A.Only one
- B.Only two
- C.All three
- D.None
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An accelerometer measures acceleration, including the pull of gravity, and each of the three actions depends on reading it. An accelerometer is a small sensor, today usually a MEMS (micro-electro-mechanical system) chip, that senses changes in speed and the direction of gravity.
Read the full explanation →Consider the following statements :
1. Carbon fibres are used in the manufacture of components used in automobiles and aircrafts.
2. Carbon fibres once used cannot be recycled.
Which of the statements given above is/are correct?
- A.1 only
- B.2 only
- C.Both 1 and 2
- D.Neither 1 nor 2
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Carbon fibre is widely used in cars and aircraft for its strength and low weight, and it can be recovered and recycled.
Read the full explanation →Which one of the following cell organelles contains DNA?
- A.Golgi apparatus
- B.Mitochondrion
- C.Lysosome
- D.Endoplasmic reticulum
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Mitochondria carry their own small, circular DNA and their own ribosomes. Mitochondria are the powerhouses of the cell, where aerobic respiration makes ATP.
Read the full explanation →Which set of vegetables is underground stem or modified stem of a plant?
- A.Potato, artichoke, round gourd
- B.Onion, garlic, carrot
- C.Potato, onion, garlic
- D.Potato, garlic, turnip
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All three are underground modified stems: the potato is a stem tuber, and onion and garlic are bulbs. A stem can be told from a root by its nodes and buds.
Read the full explanation →A sound wave having frequency of 300 Hz is travelling in an unknown medium. Its wavelength is not known. It travels a distance equal to 150 times its wavelength in time t. The value of t is :
- A.0.5 s
- B.1 s
- C.1.5 s
- D.2 s
Show answer
A wave moves forward by one wavelength in each cycle, so 150 wavelengths take 150 cycles, and 150 cycles at 300 per second take half a second.
Read the full explanation →