Students measuring the mass of a metal block record 2.985 g, 3.051 g, 3.102
g, and 3.211 g. Which other measurement of the block's mass would be most
precise?
A. 2.804 g
B. 3.1159
C. 3.418 g
D. 3.509 g

Answer:

you can burn it.

Explanation:

that is the way to change paper

Answer:

The answer is that light is faster than sound.

Explanation:

A good example is of lightning and thunder during a thunderstorm.

mark me brainliest!

Answer:

67.6 years is the time the isotope take to decay from 0.900g to 0.170g

Explanation:

The radioactive decay follows first order law:

Ln [A] = -kt + ln[A]₀

Where [A] is concentration after time t,

k is decay constant:

k = ln 2 / t(1/2)

k = ln2 / 28.1 years

k = 0.02467 years⁻¹

[A]₀ = Initial concentration.

We can replace concentration and use the mass of the isotope:

Ln [A] = -kt + ln[A]₀

Ln [0.170g] = -0.02467 years⁻¹t + ln[0.900g]

-1.667 = -0.02467 years⁻¹t

t =

The time required for the sample to reduce to 0.170 grams has been 67.75 years.

Half-life can be defined as the times required by the substance to reduce to half of its initial concentration.

The half-life can be expressed as:

Amount left = Initial amount [tex]\times[/tex] [tex]\rm \dfrac{1}{2}^\dfrac{time}{Half-life}[/tex]

From the given:

0.17 g = 0.9 [tex]\rm \times\;\dfrac{1}{2}^\dfrac{t}{28.1}[/tex]

[tex]\rm \dfrac{0.17}{0.9}[/tex] = [tex]\rm \dfrac{1}{2}^\dfrac{t}{28.1}[/tex]

0.188 = [tex]\rm (0.5)^\dfrac{t}{28.1}[/tex]

Taking log on both the sides,

log 0.188 = [tex]\rm \dfrac{t}{28.1}\;\times[/tex] log 0.5

2.411 = [tex]\rm\dfrac{t}{28.1}[/tex]

t = 2.411 [tex]\times[/tex] 28.1 years

Time = 67.75 years.

The time required for the sample to reduce to 0.170 grams has been 67.75 years.

For more information about half-life, refer to the link:

https://brainly.com/question/24710827

Answer:

3.1 moles of ammonia

18.67× 10²³ molecules

Mass = 52.7 g

Explanation:

Given data:

Number of atoms of hydrogen = 5.68×10²⁴ atoms

A) Number of molecules of ammonia = ?

Solution:

First of all we will calculate the number of moles of hydrogen.

1 mole = 6.022× 10²³ atoms

5.68×10²⁴ atoms × 1 mol / 6.022× 10²³ atoms

0.94×10¹ mol

9.4 moles of hydrogen

Moles of ammonia:

3 moles of hydrogen are present in one mole of ammonia.

9.4 moles of hydrogen = 1/3×9.4 =

3.1 moles of ammonia

Number of molecules of ammonia:

1 mole contain 6.022× 10²³ molecules.

3.1 mol × 6.022× 10²³ molecules / 1 mol

18.67× 10²³ molecules

c) Mass of sample = ?

Mass = number of moles × molar mass

Mass = 3.1 moles × 17 g/mol

Mass = 52.7 g

Answer:

True

Explanation:

All irreversible reactions go to completion because the process cannot proceed in the backward direction.

A reversible reaction is one that does not go into completion in one direction.

An irreversible direction completely uses up the reactants to form the products and goes into completion.

These reactions can only proceed in one direction and not both.

Explanation:

The halogen family and noble gases are similar in just one particular way, they are groups of non-metals. All members of these two groups are categorized as non-metals.

Here are some of the differences between them;

Answer:

2.1 moles of water formed.

Explanation:

Given data:

Moles of water formed = ?

Moles of Ni(OH) = 4.20 mol

Solution:

Chemical equation:

2Ni(OH)    →  Ni₂O + H₂O

Now we will compare the moles of Ni(OH)  with water.

             Ni(OH)           :            H₂O

                2                 :              1

              4.20             :            1/2×4.20 = 2.1 mol

2.1 moles of water formed.