Class 10 Science - Chapter Periodic Classification of Element NCERT Solutions | What were the criteria used by Mendel&ea

(a)  What property do all elements in the same column of the Periodic Table as boron have in common?
(b)  What property do all elements in the same column of the Periodic Table as fluorine have in common?

The position of three elements A, B and C in the Periodic Table are shown below –

      Group 16          Group 17
            -                       -
            -                       A
            -                       -
            B                      C

(a) State whether A is a metal or non-metal.
(b) State whether C is more reactive or less reactive than A.
(c) Will C be larger or smaller in size than B?
(d) Which type of ion, cation or anion, will be formed by element A?

Compare and contrast the arrangement of elements in Mendeléev’s Periodic Table and the Modern Periodic Table.

How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?

Which element has

(a) two shells, both of which are completely filled with electrons?
(b) the electronic configuration 2, 8, 2?
(c) a total of three shells, with four electrons in its valence shell?
(d) a total of two shells, with three electrons in its valence shell?
(e) twice as many electrons in its second shell as in its first shell?

How could the Modern Periodic Table remove various anomalies of Mendeléev’s Periodic Table?

Element X forms a chloride with the formula XCl₂, which is a solid with a high melting point. X would most likely be in the same group of the Periodic Table as

     (a) Na     (b) Mg     (c) AI     (d) Si

Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.

In the Modern Periodic Table, which are the metals among the first ten elements?

Use Mendeléev’s Periodic Table to predict the formulae for the oxides of the following elements:

    K,     C,      AI,      Si,      Ba.

What is a good source of energy?

Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?

What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

What changes can you make in your habits to become more environment-friendly?

What is the difference between a reflex action and walking?

What is the importance of DNA copying in reproduction?

If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?

Why should a magnesium ribbon be cleared before burning in air?

Define the principal focus of a concave mirror.

You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?

What precaution should be taken to avoid the overloading of domestic electric circuits?

The phenomenon of electromagnetic induction is

(a) the process of charging a body.
(b) the process of generating magnetic field due to a current passing through a coil.
(c) producing induced current in a coil due to relative motion between a magnet and the coil.
(d) the process of rotating a coil of an electric motor.

Name the sodium compound which is used for softening hard water.

What is the role of the brain in reflex action?

10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HCl. If we take 20 mL of the same solution of NaOH, the amount HCl solution (the same solution as before) required to neutralise it will be

  (a) 4 mL          (b) 8 mL          (c) 12 mL          (d) 16 mL

Design an experiment to demonstrate hydrotropism.

Why is the conversion of ethanol to ethanoic acid an oxidation reaction?

Why does the cord of an electric heater not glow while the heating element does?

What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?

Define the unit of current.