Get Excellent Results


e_learning

A sulphate salt of group two element of the periodic table is white, soft substance, which can be moulded into different shapes by making it dough. When this compound is left in open for sometime, it becomes a solid object and cannot be used for moulding purposes. Identify this sulphate salt and explain why does it show such a behaviour. Also give the equation for the reaction involved.

Answer: This substance is Plaster of Paris. When it reacts with water, it turns into gypsum which is a hard substance. Due to this, when plaster of Paris is left in open for some time, it absorbs moisture and turns into hard solid. The reaction is as follows:

CaSO4.(0.5)H2O + (1.5)H2O→ CaSO4.2H2O

SAMPLE PAPER


Read Excellent Study Materials. Use Σxcellup to study at your pace. We provide subject notes based on CBSE (Central Board of Secondary Education, India) Syllabus and NCERT (National Council Of Educational Research and Training) Books. We also provide solutions to exercise questions from NCERT Text books for various classes and various subjects. Apart from that, you will also get extra questions with answers, quizzes, videos and stories. You can post your questions in the Homework section to get answers from our experts. While our main focus is on science, mathematics and social sciences; you will also get summaries of poems, stories, drama from English and Hindi literature books.

SOLVING FROM OPTION

Question: A trader calculates his profit on the selling price and says it to be 20%. Find the actual profit.

  1. 18%
  2. 20%
  3. 25%
  4. 30%

Answer: Since profit has been calculated on selling price instead of on cost price, so correct percentage profit will be more than the calculated profit. This means that options ‘a’ and ‘b can be easily ruled out. This leaves us with options ‘c’ and ‘d’.

Let us, proceed by using the option ‘c’, i.e. 25%.
If Cost Price = Rs. 100
Then profit = Rs. 25
Then, Selling Price = Rs. 125
Now, 25 is 20% of Rs. 125; which is matching with the figure in question.
Hence, option ‘c’ is the right answer.

MORE EXAMPLES

Last Minute Preparation

Last minute revision of very short notes can be very useful for examination. This can give you the proverbial edge over your competitors. These are collection of key points from each chapter. Go through these notes just before leaving for school. You can view them while in the bus or car. You can also view them while you are riding on the pillion of your dad's bike. These notes are for those student who do not want to leave anything to chance.Click Here



Grade Eight

At present, you will get following in grade eight section:

  • Subject notes based on NCERT Books for science, mathematics, social science, English and Hindi.
  • NCERT Exercise Solution.
Go to 8th subject list

Grade Seven

At present, you will get following in grade seven section:

  • Subject notes based on NCERT Books for science, mathematics, social science.
  • NCERT Exercise Solution.
  • MCQ Quiz for different chapters of science.
Go to 7th subject list


Grade Six

At present, you will get following in class six section:

  • Subject notes based on NCERT Books for science, mathematics, social science.
  • NCERT Exercise Solution.
  • MCQ Quiz for different chapters of science.
Go to 6th subject list

Grade Eleven

At present, you will get following in class eleven section:

  • Subject notes based on NCERT Books for biology, economics, business studies.
  • NCERT Exercise Solution.
Go to 11th subject list

Class Twelve

At present, you will get following in class twelve section:

  • Subject notes based on NCERT Books for chemistry, mathematics (some selected chapters only).
  • NCERT Exercise Solution.

Funtime

As they say, fun and leisure are also essential for a healthy mind. In this section, you will get to read stories from Panchatantra and Jataka Tales. You will get to solve interesting quizzes on grammar and general knowledge.

Go to Panchatantra

Videos on Key Concepts

We have made simple videos on various key concepts. Watch these simple videos to understand complex concepts.

See a Video

Timely Help for Homework Questions

There are times when you may get stuck in a question. Submit your question in the ask question section. You will get the answer within 24 hours (holidays excluded). For this, you need to sign up at excellup; for which we do not ask for too many info from you. Rest assured, you or your parents would never get pesky calls on mobile numbers as we do not ask for your number.

Ask Questions