Test: Acids, Bases And Salts - 4 - RRB Group D / RPF Constable MCQ

Hydroxide is a diatomic anion with chemical formula OH⁻. NaOH dissociates into OH- ions in water which confirms its basic nature.

As here only red litmus is given therefore it could not indicate the acidic solution therefore it is first dipped in Dil solution of NaOH so that it may turn blue and after that we pour drops of soln if the soln is acidic it would turn blue litmus to red and if it is basic it could remain in same colour and if it is neutral it colour changes to slightly yellowish.

The above mentioned situation shows that the first shower of rain water is acidic in nature. The acid present in rain water turns petunia bud reddish purple in colour. Primarily the rain water becomes acidic due to the presence of sulfuric acid and nitric acid which is derived by the reactions of several compounds like sulfur dioxide, oxides of nitrogen etc. present in air with rain water.

Sulfuric acid on treating results in partial or complete removal of unsaturated hydrocarbons, sulfur, nitrogen, and oxygen compounds.

HCl  show acidic behaviour in aqueous solution as they dissosciate in water to produce Hydrogen ions while organic solvents do not form ions in water.

Normal, clean rain has a pH value of between 5.0 and 5.5, which is slightly acidic. However, when rain combines with sulfur dioxide or nitrogen oxides—produced from power plants and automobiles—the rain becomes much more acidic and ph becomes around 4.2 - 4.4

Bleaching powder has a pale yellow powder. It has a strong smell of chlorine. It is soluble in water but a clear solution is never formed due to the presence of impurities.

CaOCl₂ is called as bleaching powder or calcium hypochlorite chloride i.e Ca(OCl) Cl.

Solution S and R will turn phenolphthalein pink because they are basic in nature and we know that bases turn phenolphthalein pink.

Statement A is true, because  both salts are different. In statement B, acetic acid is a weak acid but ammonia is a weak base not a strong base .  So , statement second is false.

10 ml of NaOH requires 8 ml of HCl for neutralization
20 ml of NaOH will require (8/10)×20 = 16 ml of HCl

Red litmus has no action in water and turns blue in base.

Zinc reacts with dilute HCl to form zinc chloride and hydrogen gas is evolved. Hydrogen gas is colourless and odourless gas. To identify its presence a burning match stick is brought close to it and it burns with a pop sound.

  ​Zn + 2HCl = ZnCl₂ + H₂

ZnO reacts with hydrochloric acid forming zinc chloride and water. With sodium hydroxide, it forms sodium zincate and water.Zno is an amphoteric oxide,because it can react with both acids and bases.

Carbonic acid as it is a weak acid. strong acids make acidic salts with weak bases and neutral salts with strong bases while weak acids make basic salts with strong bases and neutral with weak bases.

The solution is HCl.
Egg shells contains calcium carbonate, which on reaction with HCl liberates CO₂ gas which turn lime water to milky.
CaCO₃ + 2HCl → CaCl₂ + H₂O + CO2

The venom of a honey bee contains formic acid

Metals react with acids to form salts and hydrogen gas. When curd and other sour substances are kept in a copper vessel (metal), copper reacts with the acid in it to form hydrogen gas and toxic substances which are unhealthy and unfit for human consumption. It may cause food poisoning also.

On passing excess co₂ through caco₃ (aq).the milkiness of the solution fades because of the formation of ca (hco₃)₂ calcium bicarbonate which is soluble in water and hence the milkiness of the solution fades away.

Anion Cl^- is collected at anode and H⁺ cation is collected at cathode. Trick to remember: anion at anode and cation at cathode.

The gas produced in lab is a base because when few drops of phenolphthalein is added to the gas it changes it's colour to pink and phenolphthalein only changes it's colour in basic solution .

Sulphuric acid is an example of diprotic acid. A diprotic acid is an acid that can donate two proton or hydrogen atom per molecule to an aqueous solution. 
Phosphoric acid is a Triprotic acid. They can donate three proton. 

If the water contains more H+ ions, it will become more acidic. If water contains more OH- ions, it will become more basic.

A pH value of less than 7 indicates an acidic solution, while greater than 7 indicates a basic solution. Therefore, the solution with pH = 6 is acidic and has more hydrogen ion concentration than the solution of pH = 8 which is basic.

Lemon contains citric acid. Vinegar has acetic acid. Nitric acid is also known as mineral acid. Tamarind has tartaric acid.