Class 11 New Chemistry Book
Class : 11
Chapter Name: STOICHIOMETRY
Short Questions:
Q1.Define.
Answer:
.Stoichiometry:
Stoichiometry deals with calculations of masse’s and sometimes also volumes of the reactants and products involved in a chemical reaction.
.Exponential Notation:
Exponential notation is a way of expressing the too large or too small numbers into a single number and raised to the power of the respective exponent. The power of the exponent can be either positive or negative. For Example: 90000 = 9 × 104
.Molar Volume:
At standard Temperature and Pressure (STP) the molar volume (Vm) is the volume occupied by one mole of a chemical element or a chemical compound. It can be calculated by dividing the molar mass (M) by mass density (ρ).
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Q2. Express the following number in exponential notation.
Answer
1) 3652 = 3.652 × 103.
2) 0.0231 = 2.31× 10 -2
3) 0.000072 = 7.2×10–5
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Q3. Express the following in simple words .
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Answer:
1) 3.26 × 10–3 = 0.00326
2) 1.921 × 102 = 1921
3) 1.02 × 105 = 102000
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Q4. Define rounding off data. Give various rules of rounding data.
Answer:
Definition:
Rounding off data is a method of reducing the figure from the given numeric value. Its defines as “ to reduce a number to desired significant figure and adjust the last reported digit”
Rules of Rounding Off data:
1) If the digit to be dropped is greater than 5, then add 1 to the digit to be retained .
For example:5.768 is round up to 5.77 if three significant figures are needed to be retained .
2) If digit to be dropped is less than 5, then simply drop it without changing preceding number .
For example: if 5.734 is rounded up to three significant figures, we get 5.73.
3) If digit to be dropped is exactly 5 , there are two conditions:
*if the digit to be retained is even , then just drop the 5.
For example: when 7.865is rounded up to three figures we get 7.86
* If the digit to be retained is odd , then add 1 to it .
For example: 23.35 is rounded to 23.4
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Alhumdulliah Short Questions Done
