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3 years ago

Spring day characterized by day and night of equal lengths

1 answer:

3 0

<span>Day and night are not exactly of equal length at the time of the March and September equinoxes. The dates on which day and night are each 12 hours occur a few days before and after the equinoxes.</span>

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When 100ml of M HCl is mixed with 100ml of N NaOH, the pH of the resulting solution is

RoseWind [281]

Answer:

Option d. 7

Explanation:

A mixture of a strong base and a strong acid produce a neutral salt and water.

This is the reaction of neutralization:

HCl + NaOH → NaCl + H₂O

NaCl → Na⁺ + Cl⁻

Sodium chloride is neutral salt which does not give H⁻ neither OH⁻ to medium, that's why pH is neutral.

Both ions are derivated from a strong acid and base so they do not make hydrolisis. They are a conjugate pair of a weak acid and base. The reactions can not occur:

Cl⁻ + H₂O ← OH⁻ + HCl

Na⁺ + H₃O⁺ ← NaOH + H₂O

4 0

3 years ago

Dry ice is solid carbon dioxide. Instead of melting, solid carbon dioxide sublimes according to the following equation: CO2(s)→C

GREYUIT [131]

Answer:

$m=8.79kg$

Explanation:

First of all we need to calculate the heat that the water in the cooler is able to release:

$Q=\rho * V*Cp*\Delta T$

Where:

Cp is the mass heat capacity of water
V is the volume
$\rho$ is the density

$Q=1 g/cm^3 *15000 cm^3*4.184 \frac{J}{g*^{\circ}C}*(10-90)^{\circ}C$

$Q=-5020800 J=-5020.8 kJ$

To calculate the mass of CO2 that sublimes:

$-Q=\Delta H_{sub}*m$

Knowing that the enthalpy of sublimation for the CO2 is: $\Delta H_{sub}=571 kJ/kg$

$5020.8 kJ=571 kJ/kg*m$

$m=\frac{5020.8 kJ}{571 kJ/kg}=8.79kg$

6 0

3 years ago

In which of the following cases does the reaction go to farthest to completion ?

Mashcka [7]

Answer:

$k=10^{3}$

Explanation:

k stand for equilibrium constants in terms of reaction

The higher the value of an equilibrium constant the faster the equilibrium reaction comes to completion.

Consider the example below:

$R_{1}\ + R_{2}$ ⇄ $P_{1}\ + P_{2}$

where

$The\ equilibrium\ constant\ K = \frac{P_{1}P_{2}}{R_{1}R_{2}}$

For a faster reaction the numerator i.e. the right hand side of the equation have to be higher than the left hand side (the denominator). therefore the higher the numerator, the higher the value of the equilibrium constant and the faster the reaction get to completion thus option c is correct.

5 0

3 years ago

16. What is tincture of iodine?

GalinKa [24]

Answer:

Tincture of iodine, iodine tincture, or weak iodine solution is an antiseptic. It is usually 2–7% elemental iodine, along with potassium iodide or sodium iodide, dissolved in a mixture of ethanol and water. Tincture solutions are characterized by the presence of alcohol.

Explanation:

7 0

3 years ago

The animal kingdom is large and diverse. Scientists discover new species all the time, and they need a way to classify them. The

tatiyna

The answer is D, because "Animals without a backbone are invertebrates."

4 0

3 years ago