When 0.692 g of glucose, C6H12O6, is burned in a constant volume calorimeter containing 575 g of water, the temperature rises from 21.70°C to 25.22°C. If the heat capacity of the bomb is 650 J/K, calculate the heat of the reaction, in MJ, when 1.0 mol of glucose is burned.

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

Answer: 7.8125 g
Explanation: Given:
Original amount (N₀) = 500 g
Number of half-lives (n) = 9612/1602 = 6
Amount remaining (N) = ?
N = 1/2ⁿ × N₀
N = 1/2^6 × 500
N = 0.015625 × 500
N = 7.8125 g

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: 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: 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

Answer: B. 7.2 x 10(23rd power)
Explanation:
Avogadro's number is defined as the number of particles found in an amount of substance per mole. It is the factor that relates the moles of a substance to the mass of that substance. We will use Avogadro's number to calculate the number of moles of water. as follows:
Avogadro's number = 1 mol = 6.022 x 10^23 particles.
we will use the conversion factor to calculate the number of moles of water:
1.20 = N x (1mol/6.022x10^23 particles)
N = 1.20/(1mol/6.022x10^23 particles)
N = 7.2 x 10(23rd power)

Answer: rate of reaction can be monitored by measuring the time taken for a fixed amount of sulphur to be produced
Explanation: The reaction of sodium thiosulfate with hydrochloric acid is:
Na₂S₂O₃(aq)+2HCl(aq)→2NaCl(aq)+SO₂(g)+S(s)+H₂O(l)
A precipitate of sulphur forms
Therefore rate of reaction can be monitored by measuring the time taken for a fixed amount of sulphur to be produced

Answer: musculoskeletal
Explanation: The musculoskeletal system is a functional set of skeletal bones, their connections (joints and synarthrosis) and somatic musculature. Rheumatoid arthritis affects the joints, respectively, the musculoskeletal system of the body is most affected.

Answer: A, C, E.
Explanation: A) An atomic emission spectrum occurs when an element in the gas state absorbs energy, and light that corresponds to the energies of specific electrons.
Atomic spectra occur when electromagnetic radiation is emitted or absorbed by ions, free or weakly bound atoms (in gases or vapors) => NOT in a solid state

C) The light that an element emits is made up of a limited number of narrow lines of light that produce a unique pattern, or atomic emissions spectrum, for that element.
Each elements emission spectrum is distinct because each element has a different set of electron energy levels. The emission lines correspond to the differences between various pairs of the many energy levels. The lines (photons) are emitted as electrons fall from higher energy orbitals to lower energies.

E) An atomic emission spectrum shows that pattern formed when light emitted by an element is separated into its different component wavelengths.
Atomic spectra caused by quantum transitions between different energy levels of free (weakly bound) atoms and resulting from the emission or absorption of electromagnetic radiation by them are linear, i.e. consist of separate spectral lines.