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3 years ago

How many protons, electrons, and neutrons are in calcium?

Chemistry

1 answer:

noname [10]3 years ago

3 0

Answer:

20 protons , 20 electrons and 20 neutrons

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1. Which is not an example of a physical change to a wooden stick?

Anvisha [2.4K]

The answer is C. burning the stick. This is because burning the stick will change the chemical properties of the wood, and it will not be wood anymore, it will be ash and the rest will be heart or gas.

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3 years ago

A piece of silver (Ag) metal weighing 194.3 g is placed in a graduated cylinder containing 242.0 mL of water. The volume of wate

mariarad [96]

Answer: The density of silver metal will be $10.50g/ml[\tex]Explanation:Density is defined as the mass contained per unit volume.[tex]Density=\frac{mass}{Volume}$

Given : Mass of silver = 194.3 grams

Volume of silver= volume of water displaced= $260.5-242.0=18.5mltex]Putting in the values we get:[tex]Density=\frac{194.3g}{18.5ml}=10.50g/ml/tex]Thus density of silver metal will be [tex]10.50g/ml$

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3 years ago

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Which statement explains why the bonds between nonmetals tend to be covalent? The bonds are found to be nondirectional. They hav

Alexandra [31]

Correct Answer: <span>They have small differences in electronegativity (statement 3)
Reason:
The nature of chemical bond between atoms is primarily driven by the electronegativity difference between constituent atoms. If electronegativity difference between constituent atoms is significantly higher, ionic bond formation is preferred. On other hand, low difference in electronegativity values, favours formation of covalent bond.
</span><span>
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3 years ago

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What is the velocity of a rocket that goes 700 km north in 25 second

Dmitrij [34]

Answer: 28000m/s

Explanation:

Displacement = 700 km due north = 700000m

Time = 25secs

Velocity =?

Velocity = Displacement / Time

V = 700000 / 25 = 28000m/s

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3 years ago

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A materials scientist has created an alloy containing aluminum, copper, and zinc, and wants to determine the percent composition

liubo4ka [24]

Answer:

0.8749 grams of hydrogen gas was formed from the reaction.

Explanation:

P = Pressure of hydrogen gad= 744 Torr = 0.98 atm

(1 atm = 760 Torr)

V = Volume of hydrogen gas= 11 L

n = number of moles of hydrogen gas= ?

R = Gas constant = 0.0821 L.atm/mol.K

T = Temperature of vapor = 27.0 °C = 300.15 K

Putting values in above equation, we get:

Using an ideal gas equation:

$PV=nRT$

$n=\frac{PV}{RT}=\frac{0.98 atm\times 11 L}{0.0821 L atm/mol K\times 300.15 K}$

n = 0.4374 moles

Mass of 0.4374 moles of hydrogen gas:

0.4374 mol × 2 g/mol = 0.8749 g

0.8749 grams of hydrogen gas was formed from the reaction.

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3 years ago