Which number contains four significant figures? A) 3.978 B) 0.780 C) 0.0085

Which number contains four significant figures? A) 3.978 B) 0.780 C) 0.0085 D) 1700 E) Two or more of the above numbers contain four significant figures

2 months ago

Solution 1

Guest Guest #6876568
2 months ago
Remember significant figures are all non-zero numbers. 

📚 Related Questions

What kind of charge does a cation have
Solution 1
I believe it has a positive
Solution 2
A cation is a term that indicates a positively charged ion, that essentially results when an electrically neutral atom, loses its electrons, specifically electrons from its outer shell to another atom, primarily for the purpose of ionic bonding. When this occurs, the atom that donated its electrons, now has an indifference of protons and neutrons and this results in a positively charged species.
. When 0.022189 is correctly rounded to two significant figures the number becomes
Solution 1
(Correct to two significant figures)
Particles in a liquid move around just as freely as particles in a solid.
Solution 1
It is false :D I am 95% sure
Solution 2

its false as only gas has that ability to do so

Give the structure that corresponds to the following molecular formula and 1H NMR spectrum: C4H10O2: ? 1.36 (3H, d, J = 5.5 Hz); ? 3.32 (6H, s); ? 4.63 (1H, q, J = 5.5 Hz)
Solution 1
Δ 1.36 (3H, d, J = 5.5 Hz) 

δ 4.63 (1H, q, J = 5.5 Hz) 

Note: X anY can't have hydrogen attached, so they are probably O. 

δ 3.32 (6H, s); δ 4.63 (1H, q, J = 5.5 Hz) 
There is only C2H6O2 remaining, so this must be two CH3 groups; the attachment must be as an ether, and there must be two of them: 
Consider equimolar samples of different ideal gases at the same volume and temperature. gas a has a higher molar mass than gas b
Solution 1

The question is incomplete.

This is the complete question:

Consider equimolar samples of different ideal gases at the same volume and temperature. Gas A has a higher molar mass than gas B.

Compare the pressures. Compare the rms speeds. Compare the average kinetic energies.


pressure: A = B

RMS: A < B

kinetic energies: A = B


1) Pressure:

You can deal with this part of the question on the basis of Avogaro's principle which stated that equal volumes of gases at same temperature and pressure have the same number of particles (molecules).

Also, kinetic theory of gases postulates that the particles of gas are quited separated and in consequence the volume occupied by the particles of a gas is meaningless and does not influence the total volume occupied by a fixed number of particles.

Also, you can use the equation of ideal gases pV = nRT, from which p = nRT/V. if n, T, and V are fixed, then p is fixed.

The three approaches leads to the same conclusion.

Then, pressure of gas A is equal to pressure of gas B.

2) RMS

RMS stands for root mean square speed.

It is the room mean square speed of the particles of a gas.

the RMS is related with the temperature of the gas and the molar mass per this equation:

RMS = √(3RT/M), where R is the universal constant of gases, T is the absolute temperature and M is the molar mass.

Then, the greater the molar mass, the lower the RMS, which permits you conclude that the RMS of gas A is less than the RMS of the gas B.

3) kinetic energy

Temperature is a measure of the kinetic energy.

Equal temperatures of the gas means equal kinetic energies.

The Kinetic Molecular Theory states that the average energy of molecules is proportional to absolute temperature.

So, you conclude that the same amount of gases, at the same temperature, contain equal kinetic energies.

Solution 2
Equal pressures  from the ideal gas equation (P = nRT/V) ... same moles, T and V... P must be the same. Lighter gas has greater RMS speed .... KE = 1/2mv² mass and speed inversely proportional 
Same KE .... all gases at same T have same KE 
What is the approximate h−o⋅⋅⋅⋅h bond angle in ice, where h−o is the covalent bond and o⋅⋅⋅⋅h is the hydrogen bond?
Solution 1
The H-O bond angle for ice is 109.47° and for liquid water, the bond angle of H-O is 105°. The bond angle for ice is wider than for liquid water because the structure of ice is stable when the bond angle between H and O is wider. This is the reason why liquid water expands when it turns to ice.
Solution 2
Hello there.

What is the approximate h−o

When aluminum reacts with hydrochloric acid the products that form are aluminum chloride and hydrogen gas?
Solution 1
this reaction is between a metal and an acid which typically results in a salt and the release of hydrogen gas.
Which of the following bases can remove a proton from formic acid in a reaction that favors products?
Solution 1

The bases like chloride, hydroxides and methoxide ions can  accept a proton from an acid because, they are more attracted to a proton in the negative charged form.

What is formic acid?

Formic acid is a carboxylic acid having the form HCOOH . The pKa value of formic acid is 3.74. Thus the acidity of formic acid is greater than that of acetic acid and common alcohols.

According to Bronsted- Lowry concept of acids and bases, acids are substances able to donate protons to the bases and bases accept protons from acids.

Formic acid upon deprotonation forms HCOO⁻ and it is called formate ion. Substances with higher basicity remove the protons from the carboxylic part of formic acid.

Bases containing a negative charge are highly active and will easily remove a proton from acids. Thus, bases such as  chloride, hydroxides and methoxide ions remove the H from HCOOH to form their protonated forms HCl, H₂O and CH₃OH respectively.

Other substance such as CH₃OH and CH₃NH₂ are less basic and cannot accept a proton from highly acidic HCOOH . Hence, options a, d, e are correct.

To find more about Bronsted- Lowry concept, refer the link below:



Your question is incomplete. But your complete question probably was:

Which of the following bases can remove a proton from formic acid in a reaction that favors products? Check all that apply.

a. Chloride

b. methanol

c. acetic acid

d.hydroxide ion

e. methoxide ion

f. methylamine

Solution 2
Hydroxide ion is a strong  and would react with H+ to form water 

Why dont elements in the same periods share many of the same properties?
Solution 1
It is because they have different number of valence electrons. Many properties of the element depend on that and as it's different within a period, they don't share many properties

Hope this helps!
Enter the symbol of a sodium ion, Na+, followed by the formula of a sulfate ion, SO42−
Solution 1

sodium sulphate ionic compound formula