CBSE Class 10 Science Entrance Exams Questions and Answers
CBSE Class 10 Science
QUESTIONS
CBSE Class 10 Science Entrance Exams Questions and Answers
71 Which of the following does not decrease while moving down the group of the periodic table?
A Valence electrons
B Number of shells in the atom
C Atomic radius
D Metallic character
Answer: Valence electrons
72 The elements A, B and C belong to group 2, 14 and 16 respectively, of the periodic table. Which of the two elements will form covalent bonds?
A B and C
B C and A
C A and B
D None of these
Answer: B and C
73 Which of the following is the atomic number of an element that forms basic oxide?
A 19
B 15
C 18
D 17
Answer: 19
74 Which of the following elements has 2 shells and both are completely filled?
A Boron
B Helium
C Calcium
D Neon
Answer: Neon
75 Which group elements are called transition metals?
A Group number 1 to 2
B Group number 13 to 18
C Group number 3 to 12
D Group number 1 to 8
Answer: Group number 3 to 12
76 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 Mg
B Si
C Na
D Al
Answer: Mg
77 Which of the following is the most reactive element of the group 17?
A Fluorine
B Magnesium
C Oxygen
D Sodium
Answer: Fluorine
78 What is the other name for group 18th elements?
A Halogens
B Noble gases
C Alkali metals
D Alkali earth metals
Answer: Noble gases
79 Which of the following is the correct order of the atomic radii of the elements oxygen, fluorine and nitrogen?
A F < O < N
B O < N < F
C O < F < N
D N < F < O
Answer: F < O < N
80 What happens to the electropositive character of elements on moving from left to right in a periodic table?