CBSE Class 11 Chemistry VBQs Classification Of Elements And Periodicity. Value based questions are very important and always form part of examinations and class tests. Students are requested to download the VBQs and practice them to get better marks in examinations.
UNIT – 3 (CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES)
Question 1. At present as many as 118 elements are known and the process of discovering new elements is not yet over. Under the circumstances, it becomes rather impossible to study and remember the properties of each element. Scientists felt the necessity of group elements of similar characteristics together so that if the properties of one of them are known, those of the other could be co-related. The real credit for preparing the periodic table goes to Mendeleev.
(i) Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that?
(ii) What is the basic difference in approach between Mendeleev’s periodic law and the Modern periodic law?
(iii) What values are shown by Mendeleev?
Q2. Vimla was taught in chemistry class about electron gain enthalpy. In general, the electron gain enthalpy for some third period elements (eg.P,S,Cl) are more negative than the corresponding second period members (eg.N,O,F). Vimla was totally confused and wanted to know the reason for the same. She discussed with her teacher. The teacher explained the phenomenon which makes Vimla satisfied.
(i) What would be the answer of the teacher?
(ii) Which of the following pairs of element has lesser gain electron gain enthalpy? N or O.
(iii) What values are shown by Vimla?
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