Chemistry : asked on Key1431
 15.03.2022

Which material is the best conductor of heat at room temperature?
air
water
sulfur
copper

. 5

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Chemistry
Step-by-step answer
P Answered by Master
Answer: 0.0045 mol
Explanation: Convert 30 ml to l: 30 mL = 0.03 L
Molarity = mol/l
mol = molarity * L
mol = 0.15 * 0.03 = 0.0045 mol
Answer: 0.0045 mol
Explanation: Convert 30 ml to l: 30 mL = 0.03 L
Molarity = mol/l
mol = molarit
Chemistry
Step-by-step answer
P Answered by PhD
Answer: chalcogens.
Explanation: Strontium is an alkaline earth metal, it always exhibits a degree of oxidation in its compounds +2.
Chalcogens are a group of 6 chemical elements (oxygen O, sulfur S, selenium se, tellurium te, polonium Po) that have an oxidation state of -2 => Chalcogens will combine with strontium in a ratio of 1:1.
Chemistry
Step-by-step answer
P Answered by Specialist
Answer: b. Fiona is correct because the diagram shows two individual simple machines.

Explanation:
A mechanical device using which we can change the direction or magnitude of force applied is known as simple machine.
For example, in the given diagram there are two individual simple machines.
The machine helps in changing the direction or magnitude of force applied by the man. As a result, it becomes easy for him to carry different things easily from one place to another.
Thus, we can conclude that the statement Fiona is correct because the diagram shows two individual simple machines, is correct.
Answer: b. Fiona is correct because the diagram shows two individual simple machines.

Explanation
Chemistry
Step-by-step answer
P Answered by PhD
15 moles.Explanation:Hello,In this case, the undergoing chemical reaction is:Clearly, since carbon and oxygen are in a 1:1 molar ratio, 15 moles of carbon will completely react with 15 moles of oxygen, therefore 15 moles of oxygen remain as leftovers. In such a way, since carbon and carbon dioxide are also in a 1:1 molar ratio, the theoretical yield of carbon dioxide is 15 moles based on the stoichiometry:Best regards.
Chemistry
Step-by-step answer
P Answered by PhD
Answer: 25 g
Explanation: Given:
Original amount (N₀) = 100 g
Number of half-lives (n) = 11460/5730 = 2
Amount remaining (N) = ?
N = 1/2ⁿ × N₀
N = 1/2^2 × 100
N = 0.25 × 100
N = 25 g
Chemistry
Step-by-step answer
P Answered by PhD
Answer: The product formed is potassium chloride.
Explanation:
Precipitation reaction is defined as the chemical reaction in which an insoluble salt is formed when two solutions are mixed containing soluble substances. The insoluble salt settles down at the bottom of the reaction mixture.

The chemical equation for the reaction of potassium phosphate and magnesium chloride follows (look at the picture)

2 moles of aqueous solution of potassium phosphate reacts with 3 moles of aqueous solution of magnesium chloride to produce 1 mole of solid magnesium phosphate and 6 moles of aqueous solution of potassium chloride.
Answer: The product formed is potassium chloride.
Explanation:
Precipitation reaction is defined a
Chemistry
Step-by-step answer
P Answered by PhD
Answer: B. carbon tetrachloride, CCI4
Explanation: The other options are incorrect. Let's write the correct formulas:
A. Diarsenic pentoxide - As2O5
C. Sodium dichromate - Na2Cr2O7
D. magnesium phosphide - Mg3P2
Chemistry
Step-by-step answer
P Answered by PhD
Answer: a. basic
b. basic
c. acidic
d. neutral

Explanation: Acids and bases can be classified in terms of hydrogen ions or hydroxide ions, or in terms of electron pairs. (look at the picture)
Let us note that from the pH scale, a pH of;
0 - 6.9 is acidic
7 is neutral
8 - 14 is basic

But pH= - log [H^+]
pOH = -log [OH^-]
Then;
pH + pOH = 14
Hence;
pH = 14 - pOH

a. [H+] = 6.0 x 10-10M
pH= 9.22 is basic
b. [OH-] = 30 × 10-2M
pH = 13.5 is basic
C. IH+1 = 20× 10-7M
pH = 0.56 is acidic
d. [OH-] = 1.0 x 10-7M
pH = 7 is neutral
Answer: a. basic
b. basic
c. acidic
d. neutral

Explanation: Acids and bases can be classified
Chemistry
Step-by-step answer
P Answered by PhD
Answer: 306 L
Explanation: Using the ideal gas law,
PV = nRT
where R = 0.08206 L•atm/(mol•°K), solving for n gives
n = PV/(RT)
n = (845 mmHg) (270 L) / ((0.08206 L•atm/(mol•°K)) (24 °C))

Convert the given temperature to °K and the given pressure to atm:
24 °C = (273.15 + 24) °K ≈ 297.2 °K
(845 mmHg) × (1/760 atm/mmHg) ≈ 1.11 atm

Then the balloon contains
n = (1.11 atm) (270 L) / ((0.08206 L•atm/(mol•°K)) (297.2 °K))
n ≈ 12.3 mol
of He.

Solve the same equation for V :
V = nRT/P

Convert the target temperature to °K:
-50 °C = (273.15 - 50) °K = 223.15 °K

Then the volume under the new set of conditions is
V = (12.3 mol) (0.08206 L•atm/(mol•°K)) (223.15 °K) / (0.735 atm)
V ≈ 306 L
Chemistry
Step-by-step answer
P Answered by PhD
Answer: -166.67 degrees Celsius.
Explanation: The equation of state of an ideal gas, also called the Mendeleev-Clapeyron equation, has the form: PV = nRT, where P is the density of the gas, V is the volume of the gas, n is the molar mass of the gas, T is the temperature of the gas, R is the universal gas constant = 8.314 J/(mol*K)
The gas temperature at a pressure of P = 978 mm. mercury column, molar mass n = 3.7 mol, and volume V = 25.12 liters is -166.67 degrees Celsius.

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