Which of these is caused by bacteria? A) tuberculosis B) influenza C) the common cold D) chicken pox

A tank contains 90 kg of salt and 2000 L of water. Pure water enters a tank at the rate 6 L/min. The solution is mixed and drain

sashaice [31]

Answer:

a) 90 kg

b) 68.4 kg

c) 0 kg/L

Explanation:

Mass balance:

$-w=\frac{dm}{dt}$

w is the mass flow

m is the mass of salt

$-v*C=\frac{dm}{dt}$

v is the volume flow

C is the concentration

$C=\frac{m}{V+(6-3)*L/min*t}$

$-v*\frac{m}{V+(6-3)*L/min*t}=\frac{dm}{dt}$

$-3*L/min*\frac{m}{2000L+(3)*L/min*t}=\frac{dm}{dt}$

$-3*L/min*\frac{dt}{2000L+(3)*L/min*t}=\frac{dm}{m}$

$-3*L/min*\int_{0}^{t}\frac{dt}{2000L+(3)*L/min*t}=\int_{90kg}^{m}\frac{dm}{m}$

$-[ln(2000L+3*L/min*t)-ln(2000L)]=ln(m)-ln(90kg)$

$-ln[(2000L+3*L/min*t)/2000L]=ln(m/90kg)$

$m=90kg*[2000L/(2000L+3*L/min*t)]$

a) Initially: t=0

$m=90kg*[2000L/(2000L+3*L/min*0)]=90kg$

b) t=210 min (3.5 hr)

$m=90kg*[2000L/(2000L+3*L/min*210min)]=68.4kg$

c) If time trends to infinity the division trends to 0 and, therefore, m trends to 0. So, the concentration at infinit time is 0 kg/L.

6 0

4 years ago

When a warm air mass is caught between two cooler air masses and the thicker cold air masses move underneath the thinner warm ai

almond37 [142]

An occluded front forms when a warm air mass is caught between two cooler air masses. The warm air mass is cut ofl or occluded' from the ground. The occluded warm front may cause clouds and precipitation. A swirling center of low air pressure is called a cyclone.

6 0

3 years ago

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The substance argon has the following properties: normal melting point: 83.9 K normal boiling point: 87.4 K triple point: 0.68 a

Vsevolod [243]

Answer:

The final state of the substance is a gas.

The sample is initially a liquid. One or more phase changes will occur.

Explanation:

Let's consider the phase diagram for Argon (not to scale).

A sample of argon is initially at a pressure of 49.6 atm and a temperature of 101.4 K. The pressure on the sample is reduced to 0.680 atm at a constant temperature of 101.4 K. Which of the following are true? Choose all that apply

The final state of the substance is a gas. TRUE. At 0.680 atm and 101.4 K, the substance is a gas.

The gas initially present will solidify. FALSE. Initially, Ar is present as a liquid.

The final state of the substance is a solid. FALSE.

The sample is initially a liquid. One or more phase changes will occur. TRUE. The sample is initially liquid and only one phase change will occur.

5 0

4 years ago

_______is the division of the cytoplasm at the end of mitosis.

tankabanditka [31]

Answer: D. CYTOKINESIS

Explanation:

Mitosis ends with telophase, or the stage at which the chromosomes reach the poles. ... Telophase is followed by CYTOKINESIS, or the division of the cytoplasm into two daughter cells.

6 0

3 years ago

Which of the following is a physical property of a substance?? A. Combustion B. Corrosion C. Tendency to tarnish D. Solubility

Fofino [41]

A physical property does not change the substance.

Solubility would be the answer since all of the rest are changing the substance. They all deal with bonds except solubility.

Answer: D. Solubility

6 0

3 years ago

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