Answer: 1.8 g
Explanation:
We start first, by calculating the amount of Helium
n = m/M
m = mass of Helium
M = molar mass if Helium
n = 2/4 = 0.5 moles
proceeding further, we use ideal gas law. PV = nRT
Then we have
P1V1/n1T1 = P2V2/n2T2
So that,
n2 = n1T1P2V2/P1V1T2
From the question, we know that, P1 = P2, and T1 = T2. So that,
n2 = n1v2/v1
n2 = (0.5 * 3.9) / 2
n2 = 1.95/2
n2 = 0.975 moles. With this, we can determine the mass, m2 of Helium
n = m/M
m = n * M
m = 0.975 * 3.9
m = 3.8
The difference between both masses are 3.8 - 2 = 1.8 g
Thus, 1.8 g of Helium was added to the cylinder
Sound waves will either be reflected (echo effect) or absorbed (dissipated) depending upon the material make-up of the barrier
Answer:
The horizontal component is zero.
The vertical component is 
Explanation:
Given that,
The lizard climb 7m directly up on a tree.
We know that,
The horizontal component is

The vertical component is

If the lizard climb 7m directly up on a tree then,
We need to find the components
Using given data
The horizontal component of lizard is

The vertical component is

Hence, The horizontal component is zero.
The vertical component is 
Answer:
Image result for In covalent bonds what is being shared
A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.
Explanation:
Answer:
I'd go for 'Marie drives a car'
Explanation:
Static electricity will possible form in all the scenarios, but is more likely to form when you're driving a car. This is due to the friction between the body of the car and the particles in the air around the body of the car. This is why chains are sometimes attached to fuel tankers when transporting them. The chain is made to touch the ground so that any charge built up can be safely conducted to the earth, reducing the chances of a fire outbreak due to charges igniting the fuel.