10 class acids salt and base Exam oriented Board Questions


Q. How is NH4OH used as a laboratory reagent?
Answer:  NH4OH is used to detect cations in their salt solutions by precipitating their hydroxides whose colour and solubility in excess NH4OH, identifies them.
Q. Though NaHSO4 solution releases H+ ions, why is it not called an acid?
Answer:  NaHSO4 solution is not called an acid because an acid should release only H+ ions as positive ions and not any other positive ions. But NaHSO4 is solution releases H+ ions as well as Na+ ions also as positive ion.
Q. How would you distinguish between baking powder and washing soda by heating?
Answer: Sodium hydrogencarbonate on heating gives CO2 gas which will turn lime water milky whereas no such gas is obtained from sodium carbonate.
2NaHCO3 ---Heat→ Na2CO3 + H2O + CO2     
Na2CO3.10H2O -Heat→ Na2CO3 + 10H2O
Q. Why aqueous solution of sodium carbonate is basic in nature?
Answer: Sodium bicarbonate is an amphoteric compound. Aqueous solutions are mildly alkaline due to the formation of carbonic acid and hydroxide ion:
NaHCO3 + H2O → H2CO3 + OH− 
Q. Why is an aqueous solution of ammonium chloride acidic in nature?
Answer: A basic component is the one that produces hydroxide (OH-) ions when dissolved in water. In aqueous solution of ammonium chloride, ammonium ions (NH4+) first associate with H2O and form ammonia and hydroxide ions.
NH4Cl + H2O = NH4+ + HCl
NH4+ + H2O = NH3 + OH-
Since ammonium ions produce hydroxide ions, NH4+ are considered to be the basic components.
Q. Write the composition of baking powder. What will happen if tartaric acid is not added to it?
Ans. Baking powder is a mixture of sodium bicarbonate and tartaric acid. This acid neutralizes sodium carbonate formed on decomposition of baking soda. If tartaric acid is not present in baking powder‘, the food materials such as cake will taste bitter due to the presence of sodium carbonate.
Q. Why is Plaster of Paris written as CaSO4. ½ H2O ? How is it possible to have half a water molecule attached to CuSO4?
Ans. The actual formula of Plaster of Paris is 2CaSO4.H2O which means that one molecule of H2O is associated with two molecules of CaSO4. The formula for simplicity is written as CaSO4. ½H2O.
Q. Why is acetic acid called a weak acid though there are 4 'H' atoms in the molecule? 
Answer:  Acetic acid is called a monobasic acid because only one of the 4 'H' atoms of the acid is released as H+ ion in solution.
Q. What is the action of litmus on ferric chloride solution and why?
Answer:  An aqueous solution of FeCl3 salt undergoes hydrolysis and releases H+ ions from the stronger acid HCl formed. Hence, the resulting solution is acidic and turns blue litmus turns red.
Fecl3    +   3 H2O ---->   Fe (OH)3    + 3 H Cl
  HCl                   ----->   H+                 + Cl -
Q. What is the action of Na2CO3 solution on litmus and why?
 Answer:  In solution Na2CO3 salt undergoes hydrolysis and releases OH- ions from the stronger alkali NaOH. Consequently, the resulting solution is basic and turns red litmus blue.
Na2CO3   +    2H2O  ----->   2NaOH   + H2CO3
Na OH                      ----->   Na+        +                OH-
Q. What is the action of NaHSO4 solution on litmus and why?
Answer:  Blue litmus turns red in NaHSO4 solution due to the release of H+ ions along with Na+ ions. Thus, NaHSO4 is an acid salt.
Q. When lead dioxide reacts with concentrated HCl and produces a salt and water, the reaction is not called a neutral reaction why?
Answer:  For a reaction to be called a neutral reaction the products should be only salt and water. But in the above reaction, Cl2 gas is also liberated.
Q. Define a base and acid in terms of proton.
Answer:  A base is a proton acceptor and an acid is a proton donor.
Q. What is deliquescent and hygroscopic substance?
Answer: Deliquescent substances and hygroscopic substances both are the water attracting or absorbing substances. Such substance becomes moist or wet when placed in damp or moist place by absorbing water.
Hygroscopic substances become wet while deliquescent substance dissolve after absorbing moisture. This is the major difference between these two closely related terms.
For e.g. CaCl2 is deliquescent while NaCl is hygroscopic.
Q What are hydrated salts? Give an example.
Ans: Salts containing a fixed number of water molecules in their crystal structure are called hydrated salts.
A molecule of sodium carbonate (Na2CO­3.10H2O) contains ten molecules of water. This is known as hydrated salt of sodium carbonate.
Q. What are Anhydrous and deliquescent salt?
Fore full Study: Visit: 
CBSE Class X Science
X Chemical reaction and Reactions
X Acid, Base and Salts
X Metal and Non Metals
X Electricity (Electric Currents)
X Magnetic Effects of Currents
X Source of Energy
X Biology term-1

Comments

Post a Comment

Popular Post

Obtaining and Utilization Food Class 7 Science Solved question (Basic Science Questions answers)

Image
A. Answer these questions 1. Name the three life process help living being to procure energy from food? Answer: Three life processes that help living organisms to procure energy from food are: (i) Digestion (Nutrition) (ii) Respiration (iii) Transportation 2. What are Autotrophs? Name an organism other than other than green plant that is an autotroph. Answer: Autotrophs are organisms that can prepare their own food. Chlamydomonas is a type of green algae which is an example of an autotroph, other than green plants. Cyanobacteria are also an example of autotroph. 3. Name three type of heterotrophic nutrition Answer: Three types of heterotrophic nutrition are: (i) Saprophytic nutrition (ii) Parasitic nutrition (iii) Holozoic nutrition 4. What are enzymes? Answer: Enzymes are chemical substances that act as biological catalysts and are important for carrying out biochemical processes, such as digestion, in our body
Read more

9th Atoms and Molecules Question bank By KV For CBSE Board

CHAPTER - 3 “Atoms and Molecules” 1. Laws of Chemical Combination 2. John Dalton's Atomic Theory 3. Atoms, ions & Chemical Formula 4. Mole Concept 5. Molar Mass & Avogadro constant Download Test Paper with solution CBSE Study By Jsunil ********************************************************************************* 1 Mark Questions: 1. Who gave law of conservation of mass ? 2. What term is used to represent the mass of 1 mole molecules of a substance? 3. What name is given to the number 6.023 x 10 23 ? 4. What is molecular mass? 5. Give Latin names for sodium & mercury. 6. *How many atoms are there in exactly 12 g of carbon ? 7. Define mole. 8. Calculate formula unit mass of CaCl2. [ At. Mass : Ca = 40 u , Cl = 35.5 u ] 9. Name a diatomic gas. 10. How many atoms are present in H 2 SO 4 . 2
Read more

CBSE Class 7th(VII)Science Solved Questions

Image
CBSE SCIENCE SOLVED BLOG POST BY JSUNIL FOR JSUNIL TUTORIAL,BIHAR PH: 9835859669 7th Science Hots Questions         Read   Science Nutrition in Animals   Read   Science Nutrition in Plants   Read   Transportation and Excretion   Read Transportation and Excretion   Read Transportation and Excretion   Read Motion and Time |MCQ         Read Motion and Time |Solved     Read Motion and Time |Notes     Read Motion and Time |Solved     Read Respiration in Plants and animals  Read Respiration in Plants and animals  Read Resproduction in Plants and animals  Read Acid base and salt  | MCQ      Read Acids, Bases and Salts MCQs  Read Heat and Temperature   Read Heat and Temperature   Read Water : A Precious Natural Resour
Read more

8th Conservation of Plants and animals : Science power Class 8th

Image
Book resource: Science power Class 8 th Check point-01 [Formative Assessment]        1. Define Afforestation? Answer:  The practice of planting more and more trees is called Afforestation. 2. What is desertification? What causes desertification? Answer: The phenomenon of converting fertile land into desert is called desertification. Deforestation causes desertification. 3. What is the effect of deforestation on rainfall and climate? Answer:  Deforestation increases temperature and wind velocity that reduce rainfall. These changes led to climate change. Check point-02 [Formative Assessment]        1. What is wild life? Answer: Wild life is an area where organism lives in their natural habitat like dense forest, jungle and water bodies. 2. Give one difference between endangered and vulnerable ? Answer: Endangered are those animals that are not likely survive and will soon extinct where as Vulnerable are those animal which are likely to move in enda
Read more

8th Class Cell structure and function solved questions(Biology)

Image
Q  Name the cells having branches structure. Ans Nerve Cell. Q Why cells could not be observed before seventeenth century? Ans Cells could not be observed before seventeenth century because till that time microscope was not invented. Q Why plant cell have cell wall? Ans Plant cells need protection against variations in temperature, high wind speed, atmospheric moisture, etc. They are exposed to these variations because they cannot move. That's why they have cell wall. Q Which organism has the smallest cell? Ans  Mycoplasmas, a bacteria has the smallest cell of the size of 0.1 micron i.e. ten thousandth part of a mill metre. ' Q  Which is the largest cell visible by unaided eye? Ans Ostrich egg has the largest visible cell by unaided eye. Q Name the four elements, which fonn major part of protoplasm. Ans These are carbon, hydrogen, oxygen and nitrogen. Q Give two examples of prokaryotes. Ans Bacteria and blue green algae. Q  Name the largest organ
Read more