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3 years ago

Pumice is a lightweight rock that sometimes forms when lava is very rich in _____.

Chemistry

2 answers:

Oksi-84 [34.3K]3 years ago

3 0

Answer: gases

(has bubbles in the rock)

tatuchka [14]3 years ago

3 0

This question is incomplete. Here is the complete question:

Pumice is a lightweight rock that sometimes forms when lava is very rich in _____. A. silica B. gases C. feldspar D. volcanic glass

Answer:

The correct answer is option D. volcanic glass.

Explanation:

Pumice stone is a very common stone used for construction or cleaning among other things.

This rock is formed through lava that contains water and gas and comes from the inside of a volcano, so when this lava is thrown out of the volcano it cools and hardens, and is filled with bubbles of volcanic gas.

This type of rock is low density and can float on water.

Given this information we can say that the correct answer is the option D. volcanic glass

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What happens to a line when the y-intercept is changed? Check all that apply.

tamaranim1 [39]

Answer:

As the y-intercept increases, the graph of the line shifts up;

As the y-intercept decreases, the graph of the line shifts down

Explanation:

There are two ways to think about this problem. The first way would be the graphical approach:

if we only change the y-intercept, this means we keep the same slope;
y-axis is the vertical axis;
if we change the point at which the line crosses the y-axis, we either shift it upward for a higher y-intercept or downward for a lower y-intercept.

Now, thinking algebraically, a line has the following equation in a general form:

$y = mx + b$

The y-intercept is essentially obtained when x = 0, then:

y = b:

if we increase b value, the y value increases, so the graph shifts upward;
if we decrease b value, the y value decreases, so the graph shifts downward.

5 0

3 years ago

Which of the following is not a trait of gases?

iVinArrow [24]

<span>d. tightly packed particles</span>

7 0

2 years ago

Read 2 more answers

Two scientists were competing to earn some grant money to fund their research, because

Citrus2011 [14]

Societal and economical

3 0

3 years ago

Read 2 more answers

9. If 28.56 g of K2O is produced when 25.00 g K is reactedaccording to the following equation, what is the percent yieldof the r

Mumz [18]

Answer

b. 95%

Explanation

Given:

Mass of K₂O produced (actual yield) = 28.56 g

Mass of K that reacted = 25.00 g

Equation: 4K(s) + O₂(g) → 2K₂0(s)

What to find:

The percent yield of K₂O.

Step-by-step solution:

The first step is to calculate the theoretical yield of K₂O produced.

From the balanced equation, 4 mol K produced 2 mol K₂O

Molar mass of K₂O = 94.20 g/mol)

Molar mass of K = 39.10 g/mol)

This means 4 mol x 39.10 g/mol = 156.40 g K produced 2 mol x 94.20 g/mol = 188.40 g K₂O

So 25.00 g K will produce:

$\frac{25.00\text{ }g\text{ }K\times188.40\text{ }g\text{ }K₂O}{156.40\text{ }g\text{ }K}=30.1151\text{ }g\text{ }K₂O$

Actual yield of K₂O = 28.56 g

Theoretical yield of k₂O = 30.1151 g

The percent yield for the reaction can now be calculated using the formula below:

$\begin{gathered} Percent\text{ }yield=\frac{Actual\text{ }yield}{Theoretical\text{ }yield}\times100\% \\ \\ Percent\text{ }yield=\frac{28.56\text{ }g}{30.1151\text{ }g}\times100\% \\ \\ Percent\text{ }yield=0.9484\times100\% \\ \\ Percent\text{ }yield=94.84\%\approx95\% \end{gathered}$

Therefore, the percent yield for the reaction is 95%.

3 0

1 year ago

Using appropriate chemical equation distinguish between cation and anion hydrolysis

harina [27]

Answer:

HCO3- (aq) + H2O (I) <--> H2CO3 (aq) + OH- (aq)

Explanation:

The equation to distinguish between cation and anion hydrolysis is given below :

HCO3- (aq) + H2O (I) <--> H2CO3 (aq) + OH- (aq)

The important thing to remember is their origin. The anions can react with water and can produce hydroxide ions while hydroxide ions make a solution basic.

5 0

3 years ago