Science : Ch 05 – Periodic of Classification of Elements

Which of the specified elements A, B, C, D and E with atomic number 2, 3, 7, 10 and 30 respectively affiliated to the same period?

On the basis of electronic confguration of X9 5 , the group number and period of the element ‘X‘ is:

In Mendeleev’s periodic table, gaps were left for the elements to be discovered later. Which of the subsequent element found a place in the periodic table later?

The electronic confgurations of three elements X, Y and Z are: X : 2 Y : 2, 8, 7 Z : 2, 8, 2 Which of the following is true regarding these elements?

Which of the following elements does not lose an electron with ease?

Which of the following are the characteristics of isotopes of an element?

1. Isotopes of an element have the same atomic masses.
2. Isotopes of an element have the same atomic number
3. Isotopes of an element show the same physical properties.
4. Isotopes of an element show the same chemical properties.

Three elements B, Si and Ge are:

The element with atomic number 14 is hard and forms acidic oxide and a covalent halide. To which of the following classification does the element belong?

What type of oxide would Eka-aluminium form?

Why does atomic radius decreases as we move from left to right in a period

The valency of an element vary across a period

The formulae of chlorides of Eka-silicon the elements predicted by Mendeleev.

Arrange the following elements in increasing order of their atomic radii:

The atomic number of an element is 20, its electronic configuration.

The atomic number of an element is 20, its valency is