doe delhi worksheet solution , doe delhi assessment solution science , science assessment solution
ENGLISH MEDIUM 1st ASSESSMENT :- SCIENCE
Question 1 :- Symbol of sodium , copper and magnesium are respectively ?
- Na, Cu and Mg
Question 2 :- Symbol of chlorine and chloride are respectively ?
- Cl and Cl-
Question 3 :- Formula formed by the combination of silver and iodine is ?
Question 4 :- Valency of Potassium and chlorine are respectively ?
- +1 and -1
Question 5 :- The correct formula of calcium phosphate is ?
Question 6 :- The atom of the same element having the same atomic number but different mass numbers are ?
Question 7 :- Calcium formula of aluminium hydroxide age ?
- Al (OH)3
Question 8 :- Atomic number of an atom is equal to presents in an atom ?
- Number of electrons and protons
Question 9 :- Sodium is written as any which indicate that it is ?
- atomic number 11 and mass number 23
Question 10 :- Mg(OH)2 known As ?
- Milk of Magnesia or Magnesium hydroxide
SCIENCE ASSESSMENT 2 SOLUTION
Read the given paragraph carefully and answer the following questions.
You are familiar with a number of elements like Iron, Silver, Aluminium, Sulphur, Calcium, Potassium, Copper,
Carbon, Nitrogen, Oxygen etc. They can be classified as metals and non-metals on the basis of their chemical and
physical properties. As your know that metals are always solid (except mercury- liquid at room temperature), Hard (except sodium and potassium which are soft metals) , Sonorous (except Sodium and Potassium), Lustrous (except Lead), good conductor of heat and electricity(except Graphite) malleable(can be converted into sheets), ductile (can be converted into wire).
Question 1 :- Mercury is a metal which is ……….. at room temperature.
Question 2 :- Which property of metals is used for making bells and strings of musical instruments like Sitar and Violin?
Question 3 :- A metal X is soft and can be cut with a knife. This is very reactive to air and cannot be kept open in air. Identify the element from the following
Question 4 :- Aluminium is used for making cooking utensils. Which of the following properties of Aluminium are responsible for the same?
(i) Good conductor of heat (ii) sonorous (iii) Ductility (iv) hard
- (i) and (iv)
Question 5 :- Nitrogen is a
- Non -metal
Question 6 :- It is observed that a pencil sharpener gets attracted by both the poles of a magnet while its body is not attracted by the magnet. Name the material that might have been used to make its parts.
Answer :- The Blade of sharpener is made up of iron , iron is a magnetic material because of this pencil sharpener gets attracted by the the poles of a magnet all the the body is made up of plastic that’s why its body is not attracted by the material which attract towards magnet called magnetic material .
Question 7. A magnet has two poles-north pole and south pole. State whether it will be an attraction or repulsion?
a. NORTH- NORTH. b. SOUTH – SOUTH c. NORTH- SOUTH
- NORTH – NORTH :- Repulsion .
- SOUTH – SOUTH :- Repulsion .
- NORTH – SOUTH :- Attraction .
Question 8. What are electromagnets , how its strength can be changed?
Answer :- The electromagnet is a type of magnet in which the magnetic field is produced by an electric current . the strength of an electromagnet can be increased by increasing the number of loops of wire around the iron core and by increasing the current or voltage .
Question 9. A bar magnet has no markings to indicate its poles. How would you find out near which end are its north and south poles located?
Answer :- We can find the poles of a bar magnet by suspending its freely by string . A freely suspended bar magnet always comes to rest in the north – south direction . the north facing end of the magnet is its north pole , and south facing and its south pole .
10. If a magnet is broken into two pieces. The new magnets formed will have two poles. Justify this statement.
Answer :- If a magnet is broken into two pieces the new magnets form will have two poles because magnetic monopole does not exist , so if we do not breaking process repeatedly then we will end up with each piece having unlike poles .
SCIENCE ASSESSMENT SOLUTION 3
Assertion and Reason
One labeled Assertion (A) and the other labeled Reason (R). Select the correct answer to these questions from the codes a, b, c and d. as given below.
a :- Both A and R are true, and R is correct explanation of the assertion.
b :- Both A and R are true, but R is not the correct explanation of the assertion.
c :- A is true, but R is false.
d :- A is false, but R is true
Question 1 :- Assertion(A): Quicklime reacts vigorously with water releasing a large amount of heat.
Reason(R ): The above chemical reaction is an exothermic reaction
Question 2 :- Assertion(A): Fe2O3 + 2Al ————> Al2O3 + 2Fe The above chemical equation is an example of displacement reaction.
Reason(R ): Aluminium being more reactive than Iron(Fe), displaces Iron(Fe) from its oxide.
Question 3. Assertion(A): White silver chloride turns grey in sunlight.
Reason (R): Decomposition of silver chloride in presence of sunlight takes place to form silver metal and chlorine gas.
Question 4 :- Assertion(A): The balancing of chemical equations is based on law of conservation of mass.
Reason (R ): Total mass of reactants is equal to total mass of product.
Question 5. Assertion(A): Respiration is an exothermic reaction.
Reason(R): Respiration is a process in which glucose combines with oxygen and decompose to carbon dioxide and water. This reaction also release some energy.
Question 6 :- Combustion of methane is an example of-
- Exothermic reaction
Question 7 :- When an iron nail is put in an aqueous solution of Copper Sulphate. The colour of Copper Sulphate changes to
- Blue to green
Question 8:- The solution of a substance ‘X’ is used for white wash. Substance ‘X’ is –
- Calcium oxide
Question 9:- What type of chemical reactions take place when electricity is passed through water ?
Question 10 :- Give the ratio in which hydrogen and oxygen are present in water (by volume).
SCIENCE ASSESSMENT SOLUTION :- 4
Read the passage given below and choose the correct option of Question .
When Copper vessel is exposed to moist air for a long time .it acquires green coating. Copper corrodes by
oxidation. In this process of corrosion copper reacts with moisture and gases present in the Air (oxygen and carbon dioxide) to form Copper hydroxide and Copper Carbonate which is green in colour.
This gives a green colour to the surface of copper metal.The mixture formed is basic in nature, which reacts with the acid (citric acid) present in lemon to form a Copper Citrate which is washed away with water. As a result, the green-coloured substance formed is removed from the surface of the vessel and the shining surface is seen.
Question 1. Chemical formula of Copper Carbonate is
Question 2. Copper vessel is tarnished due to
Question 3. Reaction between acid and base is called as
Question 4. Copper Citrate is a/an
Question 5. An aqueous solution turns red litmus solution blue. Excess addition of which of the following solution would reverse the change?
- Hydrochloric acid
Answer the given questions in brief.
Question 6. What will be the action of the following substances on litmus paper?
Dry NaOH, Vinegar, Lemon juice, Carbonated soft drink, Curd, Soap solution.
- Dry NaOH:- No Change
- Vinegar :- Blue litmus turns red
- Lemon juice :- Blue litmus turns red
- Carbonated soft drink :- Blue litmus turns red
- Curd :- Blue litmus turns red
- Soap solution :- Red litmus turns blue
Question 7 :- Which acid is use to be injected into the body by the sting of honey bee? Which chemical is use to neutralize its effect and why ?
Answer :- The Venom of a honey bee contains formic acid , when its stings us it injects that acid into our skin . formic acid causes immense pain and irritation however when we apply baking soda solution which is the mild base on the area . it neutralizes the formic acid and cancels its effects . As a result the sensation of pain and irritation decreases and we get some relief .
Question 8. What are indicators? Write three examples of natural and artificial indicators.
Answer :- Indicators are those substance which tell us whether a substance is acidic or basic by change in colour . for example :- litmus solution .
Example of natural indicators are :- red cabbage , turmeric , grape juice .
Example of artificial indicators are :- litmus paper
Question 9 :- What is dilution? Is it an exothermic or endothermic reaction? What are the precautions to be taken while doing dilution ?
Answer :- Dilution refers to the process of adding additional solvent to a solution to decrease its concentration . It is an exothermic reaction because large amount of heat is released .
Precaution to be taken while doing dilution :- Acid should be added to water and not water to the acid . water is added to a concentrated acid , the heat generated may causes the mixture splash out and causes burns
wear safety gloves while holding acid .
Question 10 :- What are antacids? Describe with examples. How does these help in indigestion ?
Answer :- Antacid Are mild alkalies and contain sodium hydrogen carbonate , these are used for getting relief from acidity and digestion , it react with hydrochloric acid present in the stomach and reduce the strength by the consuming some of it.
SCIENCE ASSESSMENT SOLUTION – 05
Question 1 :- Fixed number of water molecules associated with one formula unit of a substance is called as ?
- Water of crystallization.
Question 2:- Chemical formula of Gypsum is ?
Question 3 :- Colour of dehydrated Copper Sulphate is
Question 4 :- A chemical is used for disinfecting drinking water to make it free from germ. Its chemical formula is ?
Question 5 :- Slaked lime is ?
- Calcium Hydroxide.
Question 6 :- An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be-
Question 7:- The non – metal which can conduct electricity is-
Question 8:- The compounds which react with acids as well as bases to produce salts and water are called as
- Amphoteric oxides.
Question 9 :- The metal which is liquid at room temperature is
Question 10 :- The property of metals used for making strings of musical instruments like Sitar is