CHEMICAL REACTIONS AND EQUATIONS (STD.10TH) QUESTION BANK

CHEMICAL REACTIONS

(QUESTION BANK)

Choose the correct answer from the given options

· Classify the following into chemical combination and chemical displacement

a) NH₃ + HCl ® NH₄Cl                    b) Na₂O + CO₂ ® Na₂CO₃

c) CuSO₄ + Fe ® FeSO₄ + Cu          d) 2AgNO₃ + Cu ® 2Ag + Cu(NO₃)₂

· An example for chemical reaction for chemical displacement is

a) 2AgNO₃ + Cu ® 2Ag + Cu(NO₃)₂                       b) CaCl₂ + Na₂CO₃ ® CaCO₃ + 2NaCl

c) NH₄Cl ® HCl + NH₃                            d) NH₃ + HCl ® NH₄Cl            

· The reaction CuSO₄ + Zn ® ZnSO₄ + Cu

a)Double decomposition                             b) Displacement

c) Decomposition                                       d) Combination

· Following is an example for reducing agent

a)Potassium permanganate                         b) Potassium dichromate

c) Potassium metal                                     d) Potassium chloride

· Which of the following is chemical change

a) When copper sulphate crystals are heated, they become white

b) When lead nitrate is heated, we get reddish brown fumes

c) When ammonium chloride is dissolved in water, the solution gets cooled.

d) When ferrous sulphate crystals are heated, the color of the crystals change.

· Ca(OH)₂ + CO₂ ® CaCO₃ + H₂O, in this reaction the precipitate is

a)Ca(OH)₂                      b) CO₂  

c) CaCO₃                        d) H₂O

· The substance when heated in air producing reddish brown fumes is

a) Lead nitrate                         b) Ammonium chloride

c) Ferrous sulphate                  d) Calcium carbonate

· The oxidizing agent among the following is

a)Potassium permanganate [KMnO₄]                             b) Hydrogen gas [H₂]

c) Aluminium powder [Al]                                   d) Coke [C]

·  Ca(OH)₂ + 2HCl ® [X]Cl₂ + 2[Y], in this reaction [X] and [Y] are

a) Calcium and hydrogen                            b) calcium and water

c) Calcium and hydrochloric acid               d) calcium hydroxide and hydrogen

Answer the following

·  Suggest an experiment to show that water is a compound of hydrogen and oxygen.

·  Why lime water [Ca(OH)₂] turns milky when carbon dioxide gas is passed through it.

·  Write the balanced chemical equation of the chemical reaction taking place when ferrous sulphate is heated.

·  Name the oxidizing agent in the following

ZnO + C ® Zn + CO

·  Name the oxidizing agent and reducing agent in the following reaction

MnO₂ + 4HCl ® MnCl₂ + 2H₂O + Cl₂

·  What is Rancidity?

·  How can the rancidity of food be minimized?

·  What is the chemical composition of iron rust?

·  What are redox reactions? Explain

·  Explain chemical displacement and double displacement with an example for each.

·  Explain with suitable example oxidation and reduction.

·  What is chemical double displacement reaction? The reaction between barium chloride and sodium sulphate solution is an example for chemical double displacement reaction. How?

·  Classify the following into exothermic and endothermic reactions.

a) Combustion of methane                b) Reaction of calcium oxide

c) Photosynthesis                                       d) Oxidation of glucose with water in our body

·  Classify the following into chemical combination, decomposition, displacement and double displacement

¨Combustion of carbon in air

¨Reaction of barium chloride with sodium sulphate

¨Reaction of iron with copper sulphate solution

¨Reaction of iron with copper sulphate solution

¨Calcination of calcium carbonate

·  Explain the effect of oxidation with respect to the following in our daily life

1)    Iron                 2) Rancidity

·  Give one example for each for the following types of reaction and write the relevant balanced chemical equation.

Chemical combination

Chemical decomposition

Chemical double displacement

·  Identify the reducing and oxidizing agents in the following          

ZnO + C ® Zn + CO               MnO₂ + 4HCl ® MnCl₂ + 2H₂O + Cl₂

·  Express this word equation using symbols and formulae and balance it

Magnesium + Hydrochloric acid ® Magnesium chloride + Hydrogen

·  Write the names of elements [A] and [B]. What is the type of reaction? Which of the product is precipitate?

Na₂SO₄ + Ba[A]  ® BaSO₄ + [B]Cl

Write the balanced equation for

¨Calcium oxide is dissolved in water

¨Zinc metal with aqueous copper sulphate

¨Copper plate is immersed in silver nitrate solution

¨Silver chloride is exposed to sunlight

¨Barium chloride is added to dilute sulphuric acid

¨Hydrochloric acid is added to silver nitrate solution

Balance the following chemical equations

MnO₂ + HCl ® MnCl₂ + H₂O + Cl₂­

KClO₃ ® KCl + O₂

FeSO₄ ® Fe₂O₃ + SO₂ + SO₃

Pb(NO3)₂ ® PbO + NO₂ + O₂

Zn + HCl ® ZnCl₂ + H₂

Fe₂O₃ + Al ® Al₂O₃ + Fe

Draw a diagram of the arrangement of apparatus used to demonstrate the reaction of zinc granules with dilute sulphuric acid and testing hydrogen gas by burning and label any one part.

Give Reason

·  Silver articles become black when exposed to air for some days

·  Copper articles get green coating when exposed to moist air for some days.

·  When quick lime (calcium oxide CaO) is added to cold water, water begins to boil without heating.

·  Lime water [Ca(OH)₂] turns milky when carbon dioxide gas is passed through it. If excess of carbon dioxide is passed, milky nature disappears.

·  Potato chips packets are filled with nitrogen gas.

·  A shining copper vessel loses its lustre when exposed to air for several days.

·  Oxidation of glucose in our body cells is an example for exothermic reaction.

·  Silver chloride is used in black and white photography

reference : Zen Hot Model papers
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DIGESTION IN HUMAN BEINGS

LIFE PROCESSES

DIGESTION IN HUMAN BEINGS

Life Processes – The important processes carried out by the living organism to maintain and sustain life are called ‘Life Processes’.

Eg. Nutrition, Respiration, transportation, Excretion

HETEROTROPHIC NUTRITION

In this mode of nutrition organism obtain the food the outside source.

·        In amoeba food is captured at any point along the cell membrane (pseudopodia)

·        In paramecium food enter the body through one fixed point at cell membrane.

·        Saprophytes – Organisms obtain food from dead and decaying matter. Eg. fungi

·        Parasites – Organisms depends on the host for the nutrition. Eg. Leech, worms

Holozoic nutrition – In this the whole food consumed is broken down and digested with the help of enzymes. Eg. Human beings

Digestion in human beings takes place along the alimentary canal. (Mouth, oesophagus, food pipe, stomach, duodenum, small intestine, large intestine, anus)

Enzymes – These are different catalyst which helps to convert the convert the complex food molecules to the simple absorbable form.

Steps in digestion

1)    Mouth – In mouth teeth break the food in smaller particles. Saliva secreted by salivary glands mixes with the food and makes it soft. This soft ball called ‘Bolus’ is pushed towards the oesophagus.

Epiglottis, a cartilaginous flap closes the pharynx (wind pipe) while the food passes through oesophagus.

Salivary gland à amylase à starch to maltose

2)    Stomach – stomach expands when food enters into it. Gastric glands present in the inner lining of stomach secrets few digestive enzymes and helps in further digestion of food.

•           Hydrochloric acid à destroys microbes
•           Mucus à protects the inner lining of the stomach from the action of acid.
•          Pepsin à Proteins to polypeptides (chain of amino acids)
•         Rennin àMilk proteins to curd

In stomach the food is converted to semi liquid form called as ‘Chyme’.

Food is passed to the small intestine in small amounts. This is regulated by the “Sphincter Muscles”.

3)    Duodenum – This is the beginning part the small intestine. In this portion the Bile Juice from the Liver and Pancreatic Juice from the Pancreas add to the food.

Bile juice à Emulsify the fats

Pancreatic juice à         trypsin à  digests proteins

                                      Lipase à fats to simple fats

4)    Small Intestine – This is the longest part of alimentary canal. It is fitted in a compact space in coiled manner.

Walls of small intestine secrets intestinal juice, which contains different enzymes that helps in final digestion of food.

•    Proteins à Amino Acids
•    Carbohydrates à glucose
•    Fats à Fatty acids and glycerol

The walls of small intestine have numerous finger like projections called “Villi”. This increases the surface area for absorption of digested food. Villi are rich in blood vessels and absorb the digested food. This is carried to every cell of the body and utilized for obtaining energy, building new tissues and repair of old tissues.

5)    Large Intestine – The remaining food material passes to the large intestine. The Villi here absorbs the water.

6)    Anus – This is the exit of the alimentary canal. The rest of the material is thrown off the body through anus. This exit is controlled by Anal Sphincter.

·        Peristalsis – This is the contraction and relaxation movement of the muscles of the entire alimentary canal. This helps the food to move forward in the digestive track.

For the explanation of this watch the video on our youtube channel
https://youtu.be/gViM3KX6CMc

MAKE YOUR EXAM SIMPLER AND EASIER

COMMON MISTAKES (Board Exam)

The alarm rings at 5am. You jump out of your bed. Fresh up yourself and sit for the last moment revision before your final exam. The exam gets over as the scheduled time table. Then come the eager hours till the results get announced.

We find a wide smile on many faces while we find the some smiles shrink after a short time. Here pop ups few queries in the mind of the student, “what exactly is the reason for my marks not reaching up to my expectation?”

It’s a common event can say after the result of every exam. Students struggle a lot to score good marks. Their efforts are highly appreciable. They are clear with the expected marks. But many a times the actual picture of their marks card fades away their smile. What is the reason for this?

Let me share few common mistakes the students do in their exam hall.

1) STRESS

The first reason is the student enters the exam hall with the burden of tension, “It’s board exam....it’s board exam....it’s board exam.....”

Though they are well prepared for exam they don’t find themselves comfortable in exam hall. They think that writing board exam is going to be a big task which can’t be accomplished by them.

Most of the time the reason for this is parents and teachers. As soon as std.10^th or 12^th starts, the word ‘Board Exam’ falls on students ears many times for the whole year. This creates a giant picture of board exam in their mind. And with the same picture stored in their sub-conscious mind they enter the exam hall.

My dear students, board exam is not a big deal at all. Instead it’s just like your school final exam. As per my personal experience, board exam papers are easier than your school preparatory papers. My humble request to parents and teachers, first make students comfortable in the important academic years.

Help them to reduce stress rather creating haunting picture of board exam.

2) WRONGLY READ QUESTIONS

The other common mistake the students do is they read the question wrongly. The student after entering the exam hall feel a different sort of pressure. And so this is the common mistake they often do.

The best solution is keep your mind cool (techniques will be discussed later). Once you get the question paper in hand read it once. You will get a clear idea of the matter you have to right in the allotted time.

Read the questions correctly, understand exactly what is expected in the answer. And in this way complete your entire question paper.

3) HANDWRITING

We can’t say this is exactly mistake of the student. But many times bad handwriting is responsible for less score. If the handwriting is too bad it becomes difficult to read and correct the answers.

Go for handwriting improvement class well in advance. Good handwriting plays important role in overall personality development.

(Graphotherapy…best remedy to improve handwriting)

4) FINAL READING OF YOUR ANSWER SHEET

This plays very important role. After you complete your paper, read it once again before submitting it. Verify your question number and answer numbers.

Sometimes in hurry students miss one or two questions. This can be rectified in final reading and if time permits you can quickly write it.

So, students these are few simple things which you have to take care of during your exam

Keep yourself relax

Read your paper before you start solving

Write in good handwriting

Read once again before you hand it over to supervisor.

Vrushali N

Refer the link for this explanation

https://youtu.be/HYJcXTl3bak