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An element with atomic number_____ will form a basic oxide. (a) 7 (2,5) (b) 17 (2,8,7) (c) 14 (2,8,4) (d) 11 (2,8,1)
The correct answer is (d) 11 (2,8,1). The element with atomic number 11 is sodium, with electronic configuration 2,8,1. It belongs to Group 1 (alkali metals). Metals generally form basic oxides. Thus, sodium forms sodium oxide (Na₂O), a strongly basic oxide, which reacts with water to produce sodiumRead more
The correct answer is (d) 11 (2,8,1). The element with atomic number 11 is sodium, with electronic configuration 2,8,1. It belongs to Group 1 (alkali metals). Metals generally form basic oxides. Thus, sodium forms sodium oxide (Na₂O), a strongly basic oxide, which reacts with water to produce sodium hydroxide, confirming its metallic and basic nature.
See lessOn adding dilute sulphuric acid to a test tube containing a metal X, a colourless gas is produced when a burning match stick is brought near it. Which of the following correctly represents metal X?
The correct answer is (b) Zinc. When dilute sulphuric acid reacts with zinc metal, hydrogen gas is released. The reaction is: Zn + H₂SO₄ → ZnSO₄ + H₂↑. Hydrogen is a colourless gas that burns with a ‘pop’ sound when a burning matchstick is brought near it. Hence, metal X is zinc.
The correct answer is (b) Zinc. When dilute sulphuric acid reacts with zinc metal, hydrogen gas is released. The reaction is:
See lessZn + H₂SO₄ → ZnSO₄ + H₂↑.
Hydrogen is a colourless gas that burns with a ‘pop’ sound when a burning matchstick is brought near it. Hence, metal X is zinc.
Mild non-corrosive basic salt is
The correct answer is (d) NaHCO₃ (sodium bicarbonate). Sodium bicarbonate (NaHCO₃), also called baking soda, is a mild and non-corrosive base. Unlike strong bases such as sodium hydroxide or calcium hydroxide, it does not cause harm to the skin. It is commonly used in baking, medicine (antacids), anRead more
The correct answer is (d) NaHCO₃ (sodium bicarbonate). Sodium bicarbonate (NaHCO₃), also called baking soda, is a mild and non-corrosive base. Unlike strong bases such as sodium hydroxide or calcium hydroxide, it does not cause harm to the skin. It is commonly used in baking, medicine (antacids), and cleaning, showing its safe and versatile basic nature.
See lessThe colour of the solution observed after 30 minutes of placing zinc metal to copper sulphate solution is (a) Blue (b) Colourless (c) Dirty green (d) Reddish Brown
When zinc metal is placed in blue copper sulphate solution, a displacement reaction occurs because zinc is more reactive than copper. Zinc displaces copper from its salt, forming zinc sulphate, which is colourless in solution. Copper gets deposited as a reddish-brown layer, while the solution losesRead more
When zinc metal is placed in blue copper sulphate solution, a displacement reaction occurs because zinc is more reactive than copper. Zinc displaces copper from its salt, forming zinc sulphate, which is colourless in solution. Copper gets deposited as a reddish-brown layer, while the solution loses its blue colour. Hence, the correct answer is (b) Colourless.
See lessStudy the diagram given below and answer the questions: (i) Name the defect of vision represented in the diagram. (ii) Redraw the diagram and show how a corrective lens resolves this defect? Label the lens type and focal point.
(i) Defect: Myopia (nearsightedness) — image forms in front of the retina because the eye’s lens is too strong (focal length too short) or the eyeball is too long. (ii) Correction: use a concave (diverging) lens placed in front of the eye. It diverges incoming parallel rays so the eye’s lens then foRead more
(i) Defect: Myopia (nearsightedness) — image forms in front of the retina because the eye’s lens is too strong (focal length too short) or the eyeball is too long.
(ii) Correction: use a concave (diverging) lens placed in front of the eye. It diverges incoming parallel rays so the eye’s lens then focuses them on the retina.
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