Physical Science pre-Test 2020-2021

Wuy Piolcululugu<br> Give the names of two organs in the chest.<br> 1. ...............<br> 2 m

Arada [10]

Answer:

The organs present inside the chest are :

1. The lungs

2. The heart

Explanation:

The chest cavity is also called as the thoracic cavity. It is the second largest hollow space of the body.In the bottom , it is enclosed by the diaphragm.

This cavity actually contain three space each round with mesothelium , pleural cavity and precardial cavity.

This contain the lungs , the tracheobronchial tree , the heart , the blood vessels which transport the blood between the heart and the lungs.

It also contain the esophagus .

Esophagus is the path through which the food passes from the mouth to the stomach.

8 0

3 years ago

A chemist titrates 150.0 mL of a 0.2653 M carbonic acid (H2CO3) solution with 0.2196 M NaOH solution at 25 °C. Calculate the pH

xxTIMURxx [149]

Answer:

9.3

Explanation:

This is long and complicated so get ready

We are going to use the conjugate base of carbonic acid with water to make carbonic acid and OH- (Na is simply a spectator ion and is irrelavent here)

Let the conjugate base be A- and Carbonic acid be HA

A- + H20 ⇄ HA + OH-

To find the concentration of A- we must find the concentration of the reactants given. We know this will be equal because it is a strong base and all of it disassociates.

to get moles of acid we take the concentration and multiply by liters to cancel

.2653 x .150 = .039795 mol HA

Because it is at equivalence point we know the moles will be equal. We are given the concentration so we only have to solve for liters

We plug it into the equation and found: .181 L

Now use moles and combined volums to fins concentrarion which is .120 M

Now plug that use the Ka converted to Kb to find the cincentrations of HA and OH-

Ka is (10^-3.60) = 2.4E-4

Kb x Ka is 10^-14

Kb = 3.98E-11

Now we know Kb = [HA] [OH] / [A-]

Solve for this through algebra by using x for the values you dont know

youll find x^2 = 3.3E-10

X = 1.8 E -5

this is the OH- concentration

-log [oh] = pOH

pOH = 4.73

We know 14-pOH = ph so pH= 9.3

6 0

3 years ago

ASAPPP. Describe how you could determine the specific heat of a sample of a solid substance. You may

Allushta [10]

Answer:

I would use calorimetric to determine the specific heat and I would measure the mass of a sample

Explanation:

I would use calorimetry to determine the specific heat.

I would measure the mass of a sample of the substance.

I would heat the substance to a known temperature.

I would place the heated substance into a coffee-cup calorimeter containing a known mass of water with a known initial temperature.

I would wait for the temperature to equilibrate, then calculate temperature change.

I would use the temperature change of water to determine the amount of energy absorbed.

I would use the amount of energy lost by substance, mass, and temperature change to calculate specific heat.

8 0

3 years ago

How does increasing the temperature affect collisions?

ddd [48]

Combustion Have a great day!

8 0

2 years ago

Read 2 more answers

Which is the most likely to be reduced?

NISA [10]

Answer : The correct option is, $Zn^{2+}$

Explanation :

Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. That means, the loss of electrons takes place.

Or we can say that, oxidation reaction occurs when a reactant losses electrons in the reaction.

Reduction reaction : It is defined as the reaction in which a substance gains electrons. That means, the gain of electrons takes place.

Or we can say that, reduction reaction occurs when a reactant gains electrons in the reaction.

According to the electrochemical series, $Zn^{2+}$ most likely to be reduced because

Hence, the ion most likely to be reduced is $Zn^{2+}$ .

3 0

2 years ago