5. There is no water cycle where it is cold.<br> O true<br> O false

The Center for Disease Control publishes articles explaining the causes of seasonal West Nile virus. Research proves mosquitoes

Goshia [24]

Answer:

The correct answer is - Mosquitoes transmit the virus as parasites which feed on the blood of host organisms and inject the virus during feeding.

Explanation:

According to the CDC, the seasonal West Nile virus is caused by the mosquitoes of freshwater transmit this disease to humans and others. These mosquitoes are feed on the birds and pick these viruses.

These viruses stick on mosquitoes and when they feed on the blood of humans they transmit these viruses by injecting viruses into the blood of humans.

4 0

2 years ago

A particular balloon can be stretched to a maximum surface area of 1257 cm2. The balloon is filled with 3.1 L of helium gas at a

lianna [129]

Answer:

P = 0.6815 atm

Explanation:

Pressure = 754 torr

The conversion of P(torr) to P(atm) is shown below:

$P(torr)=\frac {1}{760}\times P(atm)$

So,

Pressure = 754 / 760 atm = 0.9921 atm

Temperature = 294 K

Volume = 3.1 L

Using ideal gas equation as:

PV=nRT

where,

P is the pressure

V is the volume

n is the number of moles

T is the temperature

R is Gas constant having value = 0.0821 L.atm/K.mol

Applying the equation as:

0.9921 atm × 3.1 L = n × 0.0821 L.atm/K.mol × 294 K

⇒n of helium gas= 0.1274 moles

Surface are = 1257 cm²

For a sphere, Surface area = 4 × π × r² = 1257 cm²

r² = 1257 / 4 × π ≅ 100 cm²

r = 10 cm

The volume of the sphere is :

$V=\frac {4}{3}\times \pi\times r^3$

Where, V is the volume

r is the radius

$V=\frac {4}{3}\times \frac {22}{7}\times {10}^3$

V = 4190.4762 cm³

1 cm³ = 0.001 L

So, V (max) = 4.19 L

T = 273 K

n = 0.1274 moles

Using ideal gas equation as:

PV=nRT

Applying the equation as:

P × 4.19 L = 0.1274 × 0.0821 L.atm/K.mol × 273 K

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4 0

3 years ago

An unknown compound contains 38.7 % calcium, 19.9 % phosphorus and 41.2 % oxygen. what is the empirical formula of this compound

Softa [21]

Answer: Ca3(PO4)2

Explanation:

We assume that the sample is 100.0 g.

The sample contains 38.7 g of Ca, 19.9 g of P, and 41.2 g of O as the proportions show.

Then we can calculate the number of moles of each component (n = m/atomic mass).

The number of moles of Ca = 38.7/40.078 = 0.96 mol.

The number of moles of P = 19.9/30.97 = 0.64 mol.

The number of moles of O = 41.2/15.99 = 2.75 mol.

Now, we can get the molar ratios of different components (Ca, P, and O) in the sample by dividing the number of moles of each component by the lower number of moles, that we should divide the number of moles by (0.64).