The correct option is (c) 14. Silicon has the electronic configuration 2,8,4. Here, the second shell contains 8 electrons, while the third shell contains 4 electrons, which is exactly half of the second shell, satisfying the given condition. Science important questions ...
Category: Class 10 Science
NCERT Solutions for Class 10 Science and important questions for CBSE class 10 for session 2020-2021
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The correct option is (d) 11 (2,8,1). An element with atomic number 11 is sodium. It belongs to Group 1 and forms a basic oxide, sodium oxide (Na₂O), which reacts with water to form strong alkali sodium hydroxide. Science important questions ...
The correct option is (b) Zinc. When dilute sulphuric acid reacts with zinc, it releases hydrogen gas. This colourless gas burns with a pop sound when a burning matchstick is brought near, confirming the presence of hydrogen. Class 10 Science Sample ...
The correct option is (d) NaHCO₃. Sodium bicarbonate is a mild, non-corrosive base commonly used in baking soda. It is safe, weakly alkaline, and does not harm or corrode, unlike strong bases such as sodium hydroxide or calcium hydroxide. Class 10 ...
The correct option is (b) Colourless. When zinc metal is placed in copper sulphate solution, zinc displaces copper because it is more reactive. The blue colour of copper sulphate fades, turning the solution nearly colourless as zinc sulphate forms. Class 10 ...