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3 years ago

The circulatory system provides active defense against pathogens. true or false

1 answer:

3 0

A common way pathogens can enter the body is through a cut. The circulatory system is then able to help defend the body because blood contains cells that respond to foreign materials. the respiratory system defends the body from harmful substances. Cilia and mucus also protect the body.

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Match each of the following descriptions to thecorrect element listed

Slav-nsk [51]

Answer: Please see explanation for answer

Explanation:Matching the descriptions to the correct element listed gives

Element Group Name Group No Metal/ Nonmetal/ Metalloid Description

Neon Noble gases 18 Non metal Colorless, tasteless, and odorless gas, unreactive, nonconductive.

Bromine Halogens 17 Non metal Not found as a free element (uncombined) in nature, reddish-brown liquid that vaporizes readily at room temperature to a red gas with a strong disagreeable odor.

Beryllium Alklaline earth metal 2 Metal Silvery-white, ductile, malleable, conductive solid with a high melting point for this type of element

Platinum Platimum group metals 10 Metal Silvery white, relatively soft, low density, conductive solid that is not found as a free element in nature but commonly found combined in alloys with copper or nickel

Potassium Alkali Metals 1 Metal Soft, easily cut with a knife to expose a silvery surface that rapidly oxidizes in air; never found uncombined in nature

Silicon Carbon family 1`4 Metalloid Metallic luster and grayish solid, very common in rocks and gemstones such as amethyst and opal, semiconductor

Sulfur Calcogens 16 Non metal Pale yellow, odorless, brittle solid at room temperature, nonconductor

4 0

3 years ago

In a titration experiment, 31.4 mL of 1.120 M HCOOH is neutralized by 16.3 mL of Ba(OH)2. What is the concentration of the Ba(OH

11Alexandr11 [23.1K]

Answer : The concentration of the $Ba(OH)_2$ solution is, 2.16 M

Explanation :

To calculate the concentration of base, we use the equation given by neutralization reaction:

$n_1M_1V_1=n_2M_2V_2$

where,

$n_1,M_1\text{ and }V_1$ are the n-factor, molarity and volume of acid which is $HCOOH$

$n_2,M_2\text{ and }V_2$ are the n-factor, molarity and volume of base which is $Ba(OH)_2$ .

We are given:

$n_1=1\\M_1=1.120M\\V_1=31.4mL\\n_2=2\\M_2=?\\V_2=16.3mL$

Putting values in above equation, we get:

$1\times 1.120M\times 31.4mL=2\times M_2\times 16.3mL\\\\M_2=2.16M$

Thus, the concentration of the $Ba(OH)_2$ solution is, 2.16 M

7 0

4 years ago

I am confused. Can yall help me answer this question? Also if you do, please show your work.

Eva8 [605]

Answer is: <span>volume of the acid is 0,075 L.
</span>Chemical reaction: KOH + HCl → KCl + H₂O.
V(KOH) = 30 mL · 0,001 L/mL = 0,3 L.
c(KOH) = 0,5 M = 0,5 mol/L.
c(HCl) = 2 M = 2 mol/L.
V(HCl) = ?
From chemical reaction n(KOH) : n(HCl) = 1 : 1.
n(KOH) = n(HCl).
c(KOH) · V(KOH) = c(HCl) · V(HCl).
0,5M · 0,3 L = 2M · V(HCl).
V(HCl) = 0,075 L.

8 0

3 years ago

What is the volume of stank of nitrogen that contains 17 moles of nitrogen at 34 C under 12,000Pa?

Otrada [13]

Answer:

3626.76dm³

Explanation:

Given parameters:

Number of moles of Nitrogen in tank = 17moles

Temperature of the gas = 34°C

Pressure on the gas = 12000Pa

Unkown:

Volume of the tank, V =?

Converting the parameters to workable units:

We take the temperature from °C to Kelvin

K = 273 + °C = 273 + 34 = 307k

Taking the pressure in Pa to atm:

101325Pa = 1atm

12000Pa = 0.118atm

Solution:

To solve this problem, we employ the use of the ideal gas equation. The ideal gas law combines three gas laws which are the Boyle's law, Charles's law and the Avogadro's law.

It is expressed as PV = nRT

The unknown is the Volume and we make it the subject of the formula

V = $\frac{nRT}{P}$