17. En la reacción de zinc con oxígeno, el zinc:

The nucleus of a fluorine atom has a charge of? A. +19 B. 0 C. +9 D. +1

posledela

Answer:

A fluorine atom has nine protons and nine electrons, so it is electrically neutral. If a fluorine atom gains an electron, it becomes a fluoride ion with an electric charge of -1.

7 0

3 years ago

A 5.000 g mixture contains strontium nitrate and potassium bromide. Excess lead(II) nitrate solution is added to precipitate out

scZoUnD [109]

Answer: The mass percent of potassium bromide in the mixture is 9.996%

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For lead (II) bromide:

Given mass of lead (II) bromide = 0.7822 g

Molar mass of lead (II) bromide = 367 g/mol

Putting values in equation 1, we get:

$\text{Moles of lead (II) bromide}=\frac{0.7822g}{367g/mol}=0.0021mol$

The chemical equation for the reaction of lead (II) nitrate and potassium bromide follows:

$2KBr+Pb(NO_3)_2\rightarrow PbBr_2+2KNO_3$

By Stoichiometry of the reaction:

1 mole of lead (II) bromide is produced from 2 moles of potassium bromide

So, 0.0021 moles of lead (II) bromide will be produced from = $\frac{2}{1}\times 0.0021=0.0042mol$ of potassium bromide

Now, calculating the mass of potassium bromide by using equation 1, we get:

Molar mass of KBr = 119 g/mol

Moles of KBr = 0.0042 moles

Putting values in equation 1, we get:

$0.0042mol=\frac{\text{Mass of KBr}}{119g/mol}\\\\\text{Mass of KBr}=0.4998g$

To calculate the percentage composition of KBr in the mixture, we use the equation:

$\%\text{ composition of KBr}=\frac{\text{Mass of KBr}}{\text{Mass of mixture}}\times 100$

Mass of mixture = 5.000 g

Mass of KBr = 0.4998 g

Putting values in above equation, we get:

$\%\text{ composition of KBr}=\frac{0.4998g}{5.000g}\times 100=9.996\%$

Hence, the percent by mass of KBr in the mixture is 9.996 %

5 0

3 years ago

Geologists divide Earth’s long history into smaller units that make up the geologic time scale.

aleksandrvk [35]

False

Explanation:

The geologic time scale which simplifies earth's long history is broad division of deep time. It consists of a large and small divisions.

The geologic time scale is divided into large broad categories; called eons, eras, period and epoch.
The scale is merges absolute dating of events that has happened in geologic past and their relative ages.
Broad categories on the scale are further simplified into smaller units.
Relative age puts events in the order of their appearance using a couple of geologic principles.

Learn more;

A little on geology brainly.com/question/5751004

fossils brainly.com/question/9415077

#learnwithBrainly

8 0

3 years ago

Identify the type of reaction and the products. MgF2+KNO3 ->

Airida [17]

Answer:

double replacement MgN2O6 + KF

Explanation:

7 0