1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Oliga [24]
3 years ago
8

1. The number 0.004207, when rounded off to 3 significant figures, would appear as

Chemistry
1 answer:
tresset_1 [31]3 years ago
3 0

1)

Answer:

0.00421

Explanation:

Significant figures:

The given measurement have four significant figures 1234.

All non-zero digits are consider significant figures like 1, 2, 3, 4, 5, 6, 7, 8, 9.

Leading zeros are not consider as a significant figures. e.g. 0.03 in this number only one significant figure present which is 3.

Zero between the non zero digits are consider significant like 104 consist of three significant figures.

The zeros at the right side e.g 2400 are also significant. There are four significant figures are present.

In given value the 0.00 are not significant.

when we round to three significant figures we must include 4207. The number after the third significant figure which 7 is greater than 5 so we will increase the third significant figure by one for example 0 become 1.

If the number which is next to rounded figure is 5 or grater than five the rounded figure will increase by 1.

2) In which of following  pairs of numbers does each member of the pair contain the same number of significant figures?

a) 0.0806 and 960,000

b) 71.0 and 81.00

c) 20.0 and 462

d) 0.03070 and 0.0670

Answer:

c)  20.0 and 462

Explanation:

The option c is correct because both value have same number of significant figure which are 3.

All other are incorrect because,

a) 0.0806 and 960,000

0.0806 have three significant figures and 960,000 have six significant figures .

b) 71.0 and 81.00

71.0 have three significant figures  and 81.00 have four significant figures .

d) 0.03070 and 0.0670

0.03070 have four significant figures and 0.0670 have three significant figures .

3) The mathematical meaning associated with the metric system prefixes milli , micro and nano is,

a) 10⁻², 10⁻⁴ and  10⁻⁶

b) 10⁻², 10⁻³ and 10⁻⁶

c) 10⁻³, 10⁻⁹ and 10⁻¹²

d) 10⁻³, 10⁻⁶ and 10⁻⁹

Answer:

d) 10⁻³, 10⁻⁶ and 10⁻⁹.

Explanation:

The correct option is d.

The mili is represented by "m". In metric system it is unit prefix represent thousand as 10⁻³.

This unit is adopted in 1795.

The  micro is Greek word. It is represented by symbol μ .

It is equal to 10⁻⁶.

It is presented in 1960.

The nano is equal to  10⁻⁹. It is represented by symbol "n" .

one nanometer is equal to  10⁻⁹ meter.

All other options are incorrect.

4) In which of the following measured numbers are all of zero significant?

a) 0.00480

b)0.300120

c) 6.080110

d) 99400

Answer:

option c is correct.

Explanation:

a) 0.00480

There are three significant figure in given value 480. The three zeros are not significant.

b)0.300120

There are six significant figure in given value 300120. The zero before decimal point is not significant.

c) 6.080110

There are seven significant figure in given value 6,0,8,0,1,1,0. The all zeros are significant.

d) 99400

There are three significant figure in given value 9,9,4.

5)When a substance undergoes a physical change it is always true that

a) it changes color

b) it changes state

c heat is absorbed

d) its chemical composition changes

Answer:

b) it changes state

Explanation:

Physical Change                                                                                              

The changes that occur only due to change in shape or physical properties but their chemical or internal composition remain unchanged.  

These changes were reversible.

They have same chemical property.

These changes can be observed with naked eye.

Example :

Water converting to Ice

Water converting to gas

In this water molecule remain the same only they rearrange themselves that change its state of mater not composition

6)  Object A weighs 40 grams and has a volume of 5 mL. Object B weighs 12 grams and has a volume.

Therefore,

a) A and B have equal densities.

b) B is twice as dense as A.

c) B is four times as dense as A.

d) A is more dense than B.

Answer:

Explanation:

Density:

Density is equal to the mass of substance divided by its volume.

Units:

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

D=m/v

D= density

m=mass

V=volume

Symbol:

The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

Given data:

For object A:

Mass = 40 g

Volume = 5 mL

Density = ?

Solution:

d = m/ v

d = 40 g/ 5 mL

d = 8 g/mL

The volume of object b is missing we can not determine density by just mass value.

You might be interested in
Which option is an element <br> A: carbon dioxide <br> B: Water <br> C: Air<br> D: Carbon
Ivenika [448]

Answer:

D: Carbon

Explanation:

The periodic table lists all the known elements. When looking at it, the only choice you will find is carbon. Therefore, carbon is the element.

Carbon is also by itself, just C.

Water is H2O, which is a molecule due to the 2 different elements.

Carbon Dioxide is CO2, which is a molecule due to the 2 different elements.

Air is just a mixture of different gas molecules, so therefore it is not an element.  

3 0
3 years ago
Read 2 more answers
All of the following are true except foreshocks can happen before an earthquake aftershocks can happen after an earthquake fores
Snowcat [4.5K]
Foreshocks and aftershocks can happen at the same time is not true. 
4 0
3 years ago
Write the equation for the formation of water gas
GREYUIT [131]

Answer:

the answer is C + H2O # CO + H2.

4 0
3 years ago
Read 2 more answers
What is the maximum number of electrons in the following energy level? n = 1
Lyrx [107]

Maximum number of electrons in nth energy level

\\ \sf\longmapsto 2n^2

Now

  • n=1

Max electrons

\\ \sf\longmapsto 2(1)^2

\\ \sf\longmapsto 2e^-

4 0
2 years ago
Nuclear Processes Unit Test
Finger [1]

Answer:

?

Explanation:

8 0
3 years ago
Read 2 more answers
Other questions:
  • How does vegetation slow and prevent sediment loss?
    8·1 answer
  • Sodium chloride or table salt is a compound formed when sodium loses its valence electron to chlorine. Which type of bond format
    14·2 answers
  • Which of the compounds above are strong enough acids to react almost completely with a hydroxide ion (pka of h2o = 15.74) or wit
    8·2 answers
  • Which type of ions are formed when an acid is dissolved in water?
    8·2 answers
  • Eat at Joe's! Did you know that this neon sign is experiencing a change of state? When a neon sign lights up, like the one you s
    12·2 answers
  • A 3.96x10^-24 M solution of compound A exhibited an absorbance of 0.624 at 238 nm in a 1.000-cm cuvet; a blank solution containi
    15·1 answer
  • The normal boiling point corresponds to the temperature at which both the liquid and gas are under the standard atmospheric pres
    6·1 answer
  • What are the characteristics of solution,colloids,and susensions?
    10·2 answers
  • Solid Silicon can be reacted with Nitrogen gas at a high temperature to form silicon nitride (Si3N4).
    8·1 answer
  • Do acids lose or gain hydrogen ions? <br><br>Help<br>please
    11·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!