Q40 of 52 Page 43

Identify the elements with the following property and arrange them in increasing order of their reactivity.

(a) An element which is a soft and reactive metal.


(b) The metal which is an important constituent of limestone.


(c) The metal which exists in liquid state at room temperature.

Sodium (Na) or Potassium (K) [Alkali metals such as sodium (Na) and potassium (K) are soft and reactive.] (b) Calcium (Ca) [The chemical formula of limestone is CaCO3. Hence calcium (Ca) would be an important constituent of limestone.] (c) Mercury (Hg) [Mercury (Hg) is the only metal that exists in liquid state at room temperature.]


Increasing order of their reactivity: Since reactivity of metals decreases from left to right in a period therefore increasing order of reactivity would be Hg < Ca < Na/K.

More from this chapter

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38

Write the formula of the product formed when the element A (atomic number 19) combines with the element B (atomic number 17). Draw its electronic dot structure. What is the nature of the bond formed?

 39

Arrange the following elements in the increasing order of their metallic character Mg, Ca, K, Ge, Ga

 41

Properties of the elements are given below. Where would you locate the following elements in the periodic table?

(a) A soft metal stored under kerosene.


(b) An element with variable (more than one) valency stored under water.


(c) An element which is tetravalent and forms the basis of organic chemistry.


(d) An element which is an inert gas with atomic number 2.


(e) An element whose thin oxide layer is used to make other elements corrosion resistant by the process of “anodising”.

 42

An element is placed in 2nd Group and 3rd Period of the Periodic Table, burns in presence of oxygen to form a basic oxide.

(a) Identify the element.


(b) Write the electronic configuration.


(c) Write the balanced equation when it burns in the presence of air.


(d) Write a balanced equation when this oxide is dissolved in water.


(e) Draw the electron dot structure for the formation of this oxide.