Particles of sand or dust rubbing across the surface of rocks is called:

What are the characteristics of an extrusive rock

olya-2409 [2.1K]

Extrusive Rocks. Igneous rocks which form by the crystallization of magma at the surface of the Earth are called extrusive rocks. They are characterized by fine-grained textures because their rapid cooling at or near the surface did not provide enough time for large crystals to grow.

5 0

3 years ago

How do you determine the valence electrons? Ex. Li=?, Be=?, N=?, O=?, F=? (List the charges)

JulsSmile [24]

Find a periodic table of elements. ... Label each column on the periodic table of elements from 1 to 18. ... Find your element on the table. ... Use the group numbers to determine the number of valence electrons. imgres

4 0

3 years ago

Read 2 more answers

1. Compound A contains 14 g of nitrogen for each 16 g of oxygen. Compound B contains 14 g of nitrogen for each 32 g of oxygen. W

Sever21 [200]

Answer:

The lowest whole number mass ratio of nitrogen that combines with a given mass of oxygen is 1:1

Explanation:

In compound A, we have 14 g of nitrogen combine with 16 g of oxygen

In compound B, we have 14 g of nitrogen combine with 32 g of oxygen

Therefore, we have

A B

Ratio of molar masses 14:16 14:32

Mass of O that combine with 1 g of N 1.14 2.29

Dividing by the smallest mass ratio 1 2

Therefore the lowest whole number mass ratio at which oxygen and nitrogen can combine = 1:1.

4 0

3 years ago

Enter your answer in the provided box. The atomic masses of 63Cu (69.17 percent) and 65Cu (30.83 percent) are 62.94 and 64.93 am

dybincka [34]

Answer: The average atomic mass of copper is 63.55 amu.

Explanation:

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows:

$\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i$ .....(1)

For $_{29}^{63}\textrm{Cu}$ isotope:

Mass of $_{29}^{63}\textrm{Cu}$ isotope = 62.94 amu

Percentage abundance of $_{29}^{63}\textrm{Cu}$ = 69.17 %

Fractional abundance of $_{29}^{63}\textrm{Cu}$ isotope = 0.6917

For $_{29}^{65}\textrm{Cu}$ isotope:

Mass of $_{29}^{65}\textrm{Cu}$ isotope = 64.93 amu

Percentage abundance of $_{29}^{65}\textrm{Cu}$ = 30.83 %

Fractional abundance of $_{29}^{65}\textrm{Cu}$ isotope = 0.3083

Putting values in equation 1, we get:

$\text{Average atomic mass of Copper}=[(62.94\times 0.6917)+(64.93\times 0.3083)]\\\\\text{Average atomic mass of copper}=63.55amu$

Hence, the average atomic mass of copper is 63.55 amu.

4 0

3 years ago

What is NOT true for a catalyst? 1. A catalyst increases the rate of a chemical reaction by decreasing activation energy. 2. A c

Harrizon [31]

Answer:

3. A catalyst can convert an endothermic reaction into an exothermic reaction.

Explanation:

What is NOT true for a catalyst?

1. A catalyst increases the rate of a chemical reaction by decreasing activation energy. TRUE. A positive catalyst increases the reaction rate by decreasing the activation energy.

2. A catalyst is not consumed in chemical reactions. TRUE. A catalyst is recovered unaltered at the end of the reaction.

3. A catalyst can convert an endothermic reaction into an exothermic reaction. FALSE. A catalyst cannot modify the enthalpy of a reaction.

4. A catalyst may be used in the solid, liquid or gaseous phase. TRUE. If the catalyst is in the same phase as the reaction, the catalysis is homogeneous. Else, the catalysis is heterogeneous.

8 0

3 years ago