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
HBr is the most powerful and dangerous acid .
Explanation:
A strong acid is one that instantly disunites or grants its protons in suspension. HBr is a strong acid. HBr is powerful than HCl or HF because the overlapping of a 1s-orbital and a 4p-orbital is surprisingly small, thus the binding is weak so splitting is very easy..
Answer:
i). Inverted
ii). Magnification of the image = -0.5
iii). Real
Explanation:
As shown in the ray diagram attached,
An object AB has been placed in front of converging lens (convex lens) at u = 30 cm.
F (Focus) of the lens is at 10 cm. So F = 10 cm
By analyzing the ray diagram we can measure the distance of the image on the other side of the lens (By counting the small blocks of the graph)
V = 15 cm
Characteristics of the image is:
i) Inverted
ii) Magnification of the image = 
= -0.5
ii) Real
Protons and neutrons have similar mass
Electrons are smaller then a proton or a neutron
