CHEMISTRY HIGH SCHOOL

At room temperature, none of the metals area. soft.
b. liquids.
c. malleable.
d. gases.

Answers

Answer 1

Answer:

Answer : At room temperature, none of the metals are gases.

Explanation :

The properties of metals are :

Generally all the metals are solid at room temperature but with exception, the mercury is liquid at room temperature.

Generally all the metals are hard but with the exception, sodium and potassium are soft and easily cut with the knife.

The metals are malleable, ductile, lustrous in nature.

Metals are good conductor or heat and electricity.

Hence, At room temperature, none of the metals are gases.

Answer 2

Answer:

Answer: Option (d) is the correct answer.

Explanation:

It is known that most of the metals are solid at room temperature but with a few exceptions like mercury is a liquid at room temperature and sodium is a soft metal as it can be cut with a knife.

Also, metals are malleable in nature that is, they can be shaped into thin sheets.

But metals are never gases. Hence, we can conclude that at room temperature, none of the metals are gases.

Answer:

3 US Cups = 720 ml.

Explanation:

Officially, a US Cup is 240ml (or 8.45 imperial fluid ounces.)
3 x 1 US Cup = 3 US Cups
1 US Cup = 240 ml.
∴ 3 US Cups = 3 x 240ml
= 720 ml.

What is the identity of a sample that has a mass of 8.97 g and a volume of 0.79 cm3?A.copper
B.gold
C.lead
D.iron

Answers

Answer: The correct option is Option C.

Explanation:

To identify the sample, we will determine the density of the unknown sample and match it with the specific densities. The equation used to calculate the density of a sample is given by:

$Density=(Mass)/(Volume)$

We are given:

Mass of the sample = 8.97 g

Volume of the sample = $0.79cm^3$

Putting values in above equation, we get:

$\text{Density of the sample}=(8.97g)/(0.79cm^3)=11.35g/cm^3$

This value of density matches the specific density of lead.

Hence, the correct option is Option C.

Calculate the density:

$m=8.97 \ g \nV=0.79 \ cm^3 \n \n\rho=(m)/(V)=(8.79 \ g)/(0.79 \ cm^3) \approx 11.35 \ (g)/(cm^3)$

It's the density of lead, so the answer is C.

Many laboratory gases are sold in steel cylinders with a volume of 43.8 L. What mass (in grams) of argon is inside a cylinder whose pressure is 17615kPa at 23∘C?

Answers

It's very simple... if we remember value of Universal Gas Constant R and Ideal Gas Law, so...

Ideal Gas Law
pV = nRT, where:
p - pressure (in kPa),
V - volume (in L),
n - number of moles (in mol),
R - universal cas constant (in kPa * L / mo l* K),
T - temperature (in K)

n = m/M, where:
n - number of moles,
m - mass (in grams),
M - molar mass of ingredient (in g/mol) - you find this at Periodic Table.

pV = nRT ---> pV = mRT/M ---> pVM = mRT ---> pVM/RT = m

p = 17615 kPa
T = 273.15 + 23 = 296.15 K
V = 43.8 L
R = 8.314 kPa * L / mol * K
M (for argon) = 39.948 g/mol

and

m = (17615 kPa * 48.3 L * 39.948 g/mol) / (296.15 K * 8.314 kPa * L / mol * K)
m = 13803.93 grams of Argon

Aerial fireworks contain gunpowder and chemicals that produce colors. What elements would be responsible for producing red, green, and yellow colors?

Answers

The chemicals responsible for the red flame have been strontium, the green flame has been produced by barium, and sodium has been responsible for the yellow flame.

Aerial fireworks are produced by chemical change. The fireworks have been composed of gun powder and chemicals which provide color to the reaction. The gun powder has been composed of Potassium nitrate, copper, and sulfur. The combustion reaction takes place with gunpowder and heat energy. The reaction results in the explosion of the fireworks.

The fireworks have been produced in varying colors due to the chemicals present in them. The chemical change for the transition from one substance to another and results in the colorful lights.

The chemicals responsible for the red flame have been strontium, the green flame has been produced by barium, and sodium has been responsible for the yellow flame.

For more information about aerial fireworks, refer to the link:

brainly.com/question/15790133

Final answer:

Strontium or Lithium compounds produce red color, Barium compounds produce green color, and Sodium compounds produce yellow color in aerial fireworks.

Explanation:

The elements responsible for producing red, green, and yellow colors in aerial fireworks are:

Red color: Strontium or Lithium compounds are used to produce a red color.
Green color: Barium compounds are used to produce a green color.
Yellow color: Sodium compounds are used to produce a yellow color.

Learn more about Chemistry of fireworks here:

brainly.com/question/30067466

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What is the energy change that will occur when 25.5 grams of oxygen gas (O2) react with excess methane (CH4) according to the reaction below? CH4 + 2 O2yields CO2 + 2 H2O delta H = -889 kJ/mol

Select one:
a. 354 kJ of energy will be given off by the reaction
b. 354 kJ of energy will be absorbed by the reaction
c. 708 kJ of energy will be given off by the reaction
d. 708 kJ of energy will be absorbed by the reaction

Answers

amount of CH4 is excess, so no need to worry about it
but the limiting factor is the Oxygen

according to stranded equation,

CH4 + 2 O2 --> CO2 + 2 H2O ΔH = -889 kJ/mol

just by taking proportions

(-889 kJ/mol) / 2 x 0.8 mol = - 355.6 kJ

so i think the answer is (a)

The science of using tree rings to determine absolute age is calleda. disconformity.
b. radiometric dating.
c. dendrochronology.
d. radioactive dating.

Answers

Option c. dendrochronology

tree rings or dendrochronology they allow to use it in calibration for carbon-14 on temporal placements of fragments of wood (from long dead trees).

Example Bristle cone pines (1957) 4723 years old

The best answer to the question that is being presented above would be letter c. Dendochronology is the science of using tree rings to determine absolute age. All the others are other forms of dating that would determine the tree's age.

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