CBSE Class 10 - Chemistry - 23 HOTS Questions on Chemical Reactions You Must Know - Q and A (#cbsenotes)

23 HOTS Questions on Chemical Reactions You Must Know

Class 10 - Chemistry - Q & A

Q1: A white coloured water insoluble substance X on reacting with dilute H₂SO₄ released a colourless and odourless gas accompanied by brisk effervescence. When the gas was passed through water, the solution obtained turned blue litmus red. On bubbling the gas through lime water, it initially became milky and milkiness disappeared when the gas was passed in excess. Identify the substance X‘. Write its chemical equations of the reactions involved.

Answer: Calcium carbonate on reacting with dilute sulphuric acid releases a colourless and odourless gas carbon dioxide accompanied  by brisk effervescence.

The chemical equation for this reaction is
CaCO₃ + H₂SO₄ → CaSO₄ + H₂O + CO₂

Ca(OH)₂(aq) + CO₂(g) → CaCO₃(s) + H₂O(l)
milky

CO₂ (g) + CaCO₃ (s) + H₂O (l) ⇌ Ca(HCO₃)₂ (aq)
(colourless)



Q2: Ahmad took a magnesium ribbon (cleaned) and burned it on a flame. The white powder formed was taken in a test tube and water was added to it. He then tested the solution formed with red and blue litmus paper. What change was seen? Why?


Answer:
⒜ Red litmus paper turned blue.
⒝ Blue litmus paper remained blue.

This is because the magnesium ribbon on burning in air forms the white magnesium oxide. MgO when dissolves in water, it forms magnesium hydroxide, which is basic in nature.

2Mg + O₂ → 2MgO

MgO + H₂O → Mg(OH)₂ (aq) + H₂(g)

CBSE Class 8 – Science – Microorganisms – Friends or Foes (Worksheet) (#cbseNotes)

Microorganisms – Friends or Foes (Worksheet)

Fill in the blanks 

1. Study of Microorganisms :  __________________


2. The size of bacterium is 3.5 microns =   ___________  mm       =         ___________ m


3. Microbes are divided into four categories:
i. _____________ ii. _____________
iii. _____________ iv. _____________


4. Viruses live on __________ line of living and non-living. They do not own _______ apparatus. They enter the body of living cell and start ___________.


5. The living cell inside which the virus grows and multiplies is known as ________.


6. Study of viruses is called ___________.

CBSE Class 12 - Computer Science - C++ Practical Class Design Snippet-4 (#cbseNotes)

C++ Practical
Class Design Snippet-4

Question :  Write a program that reads a file consisting of three columns of integers and called DATA.DAT

The file does not contain column labels and your application should meet these requirements:

1. An error message is displayed if the file cannot be opened.
2. When the value of the second column is zero, display the value read for the third column, and stop reading data from the file.
3. The input file stream is closed before the program code.
4. The program should not use any ifstream class member functions

Answer:

CBSE Class 12 - Informatics Practices Syllabus (2017-18) (#cbseNotes)

Informatics Practices Syllabus (2017-18)

CBSE Class 12 Informatics Practices

Here presents the prescribed syllabus for Class 12 Informatics Practices for the curriculum 2017-18.

CBSE Class 6 - Maths - Playing With Numbers - Worksheet (#cbseNotes)

Playing With Numbers 

(Natural Numbers and Whole Numbers)

Worksheet

Fill in the blanks

1. The set of numbers 1, 2, 3, 4... are called n________ numbers or c_________ numbers.


2. The smallest whole number is ________


3. The smallest natural number is ________


4. There is ______ greatest number(s) in the number system. (many/no/one)

CBSE Class 8 - Science - Coal and Petroleum (Q and A) (#cbseNotes)

Coal and Petroleum

(NCERT Exemplar  Q & A)

Petroleum Refinery

Question 1: You are provided with a mixture of petroleum and water. Can you suggest a method to separate the two?

Answer: Decantation


Question 2: What does CNG stand for and why is it considered to be a better fuel then petrol?

Answer: CNG stands for compressed natural gas. It is considered to be a better fuel because it is less polluting.


Question 3: Name the petroleum product used as fuel for stoves, lamps and jet aircrafts.

Answer: Kerosene is used as fuel for stove,lamps and jet aircrafts.


Question 4: Fill in the blanks in the following sentences.

1. Coal is one of the ________ used to cook food.
2. When heated in air, coal burns and produces mainly _________ gas.
3. Coal Tar is a black, thick - with an ________ smell.
4. Petroleum, ______ and _______ are fossil fuels.
5. Forest and coal are _________ natural resources.

CBSE Class 11 / NEET/ PMT - Biology - Ch 7 - Animal Tissues - Part 1 (Very Short Question and Answers) (#cbseNotes)

Animal Tissues (Part-1)

Very Short Q & A 

Q1: Define tissue?

Answer: A group of cells similar in structure, function and origin.


Q2: Can cells in a tissue be dissimilar in structure or function?

Answer: Yes the tissue cells can be dissimilar in structure and function but they are always similar in origin.


Q3: Who coined the word 'animal tissue'?

Answer: Bichat

😇 Note:
Marie François Xavier Bichat, a french anatomist. He is also known as father of histology. Unfortunately he died very young at the age of 30.