Some basic concept of chemistry Part 2

A measurement which on repetition gives same or nearly same result is

called

• Accurate measurement

• Average measurement

• Precise measurement

• Estimated measurement

How scientific notation is represented ?

• N

• $\frac{N}{10^n}$
  

• N ×10

• $N\times10\ ^n$

Measurement which is close to true value is called as _____.

• Exact

• Precise

• Average

• Accurate

In Avogadro’s law volume is directly proportional to _____.

• Pressure

• Number of moles

• Volume

• Temperature

Which of the following rule is incorrect for signifcant FIgure?

• All zeros between the significant.

• All zero digits are significant .

• Leading zeros which are present to the left of the

• For a number, without decimal point,the zeros after nonzero digit are not significant. e.g. 65400 has three

  significant figures.

Identify incorrect representation of scientific notation among the following

• $0.00016→1.6×10^{-4}$

• $232.508→2.325×10^2$

• $234000→2.34×10^4$

• $0.0048→4.8×10^{-3}$

Which of the following is true in a balanced chemical reaction ?

• Atoms are conserved.

• Mass is conserved.

• Molecules are conserved.

• A and B are both correct.

Which method is used to separate the component from the mixture ?

• Crystallization

• Distillation

• Filtration

• All of the above

How much molecules are present in 15 L of 

 $H_2$   gas at STP ?

• 4.033× $10^{23}$  

• 1.344× $10^{23}$  

• 1.505× $10^{23}$  

• 1.882× $10^{23}$  

How many number of oxygen atoms are present in 4.4 gm of CO ?

• $12\times10^{23}$

• $6\times10^{23}$

• $1.2\times10^{23}$

• $6\times10^{22}$