A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH paper yellowish-orange. Which of the following would change the colour of this pH paper to greenish-blue:
4. An antacid
A student noted his observations regarding the acidic or basic nature of salts as below: (I) Sodium chloride is a neutral salt (II) Ammonium chloride is a basic salt (III) Sodium carbonate is a neutral salt (IV) Copper sulphate is an acidic salt Select the incorrect observations:
1.Both (I) and (III) (b) (c) (d)
2.Both (II) and (III)
3.Both (I) and (IV)
4.Both (II) and (IV)
A visually challenged student has to perform a lab test to detect the presence of acid in a given solution. The acid-base indicator preferred by him will be:
1. Blue litmus
3.Red cabbage extract
Acids and bases represent two important classes of chemical compounds. In every day life, acids and bases play a role in everything from the digestion of the foods you eat to the function of the medicine you take and even the cleaning products you use. Without acids and bases, many of the products in your home today would not have much use. Acids and bases are also important in atmospheric, geological, and physiological processes because they have unique chemical properties. Acids and bases have unique chemical properties because of the atomic composition of these compounds and how these compounds interact with other atoms and molecules. The pH of some common substances is shown below:
1.The nature of calcium phosphate present in tooth enamel is:
Alloys are homogeneous mixtures of a metal with a metal or non-metal. Which among the following alloys contains non-metal as one of its constituents?
An electrolytic cell consists of: (I) Positively charged cathode (II) Negatively charged anode (III) Positively charged anode (IV) Negatively charged cathode
1. (I) and (II)
2.(III) and (IV)
3.(I) and (III)
4.(II) and (IV)
An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept Â¡n open air. It reacts vigorously with water. Identify the element from the following:
Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of:
Generally, metals are soLid in nature. Which one of the following metals is found in Liquid state at room temperature?
If 10 mL of H2SO4 is mixed with 10 mL of Mg(OH)2 of the same concentration, the resultant solution will give the following colour with a universal indicator:
Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining? (I) Au (II) Cu (III) Na (IV) K
1.(I) and (II)
2.(IV) and (III)
3.(II) and (III)
4. (II) and (IV)
Neetuâ€™s friend suffered a fracture in her foot while riding her bicycle. She had to be admitted to the nursing home and the doctor plastered her foot. The chemical formula for Plaster of Paris is:
Sandhya took three beakers A, B and C containing zinc sulphate, silver sulphate and iron(ll) sulphate solutions respectively. Copper pieces were added to each beaker. The solution will appear blue in the case of:
4.Beakers B and C [Diksha]
Sodium hydrogen carbonate when added to acetic acid evolves a gas. Which of the following statements are true about the gas evolved? (I) It turns lime water milky. (II) It extinguishes a burning splinter. (III) It dissolves in a solution of sodium hydroxide. (IV) It has a pungent odour.
1.(I) and (II)
2.(I), (II) and (III)
3.(II), (III) and (IV)
4.(I) and (IV)
Stainless steel is a very useful material in our life, in stainless steel, iron is mixed with:
1.Mi and Cr
2.Cu and Cr
3.Mi and Cu
4.Cu and Au
Take about 2 mL of dilute NaOH solution in a test tube and a small amount of copper oxide in a beaker. Add two drops of phenolphthalein solution in the test tube. Add dilute HCl solution in both the test tube and the beaker drop by drop while stirring. Now add a few drops of NaOH to the mixture in the test tube
1.The solution turns pink in colour
2.The solution turns colourless
3.The solution turns red
4.The solution turns yellow
To protect against tooth decay we are advised to brush our teeth regularly. The nature of the toothpaste commonly used is:
What happens when calcium is treated with water? (I) It does not react with water. (II) It reacts violently with water. (III) It reacts Less violently with water. (IV) Bubbles of hydrogen gas formed stick to the surface of calcium.
1.(I) and (IV)
2.(II) and (III)
3.(I) and (II)
4.(III) and (IV)
What happens when the solution of an acid is mixed with the solution of a base in a test tube?
1.The temperature of the solution increases
2.The temperature of the solution decreases
3.The temperature of the solution remains the same
4. Salt formation takes place
When we smile, our teeth become visible. So, we should ensure that we have a beautiful set of teeth as it makes our smile even more beautiful! Tooth enamel is the thin outer covering of the tooth. This tough shell is the hardest tissue in the human body. Enamel covers the crown which is the part of the tooth thatâ€™s visible outside of the gums. Calcium phosphate is present in tooth enamel. Its nature is:
Which among the following is not a base?
Which metal can be displaced by copper from Its salt solution? (I) Silver (II) Magnesium (III) iron (IV) Iron Correct options are:
1.(I) and (II)
2.(I) and (III)
3.(II) and (III)
4. (I) and (IV)
Which of the following is/are true when HCl(g) is passed through water? (I) It does not ionise in the solution as it is a covalent compound. (II) It ionises in the solution. (III) It gives both hydrogen and hydroxyl ions in the solution. (IV) It forms hydronium ion in the solution due to the combination of hydrogen ion with water molecule.
3.(II) and (IV)
4.(III) and (IV)
Which of the following oxide(s) of iron would be obtained on the prolonged reaction of iron with steam?
4.Fe2O3 and Fe3O4
2.Sonorous in nature
4.Sulphuric acid [Diksha]
1.Sodium carbonate (washing soda) is used in glass, soap and paper industries.
2.It is used in the manufacture of sodium compounds such as borax.
3.Sodium carbonate can be used as a cleanÂ¬ing agent for domestic purposes.
4.It is used for disinfecting water.
While performing experiments in chemistry lab, one should always wear a laboratory coat and be very careful while performing experiments. Some students have the bad habit of creating nuisance for other students which distracts the students and may cause serious accidents such as spilling of acid or can cause burn injuries. If a few drops of concentrated acid accidentally spills over the hand of a student, what should be done?
1.Wash the hand with a saline solution
2.Wash the hand immediately with plenty of water and apply a paste of sodium hydrogen carbonate
3.After washing with plenty of water, apply a solution of sodium hydroxide on the hand
4.Neutralise the acid with a strong alkali
Zinc granules on treating with an acid X, form zinc sulphate (ZnSO4) salt along with the evolution of a gas Y, which burns with a pop sound when brought near to a burning candle. Identify acid X and gas evolved Y.
1.X-sulphuric acid and Y-oxygen gas
2.X-hydrochloric acid and Y-oxygen gas
3. X-sulphuric acid and Y-hydrogen gas
4.X-hydrochloric acid and Y-hydrogen gas [Diksha]