Answer : Option A) Atomic number of Arsenic is 33.
Explanation : Arsenic contains same number of protons in its atomic nucleus. In arsenic there are 33 protons found in the atomic nucleus. Hence, the atomic number will be 33. It has 5 valence electrons in its outermost shell, which is also called as valence shell. So, its valency becomes 5.
The energy change if 84.0 g of CaO react with excess water is 98KJ of heat is released.
calculation
heat = number of moles x delta H
delta H = - 65.2 Kj/mol
first find the number of moles of CaO reacted
moles = mass/molar mass
the molar mass of CaO = 40 + 16= 56 g/mol
mass = 84 g
moles therefore = 84 g/56 g/mol =1.5 moles
Heat is therefore = 1.5 moles x -65.2 = - 97.8 Kj = -98 Kj
since sign is negative the energy is released
The average speed is 160 meters a minute.
Answer:
300000Pa or 3×10^5 Pa
Explanation:
Since the problem involves only two parameters of volume and pressure, the formula for Boyle's law is suitably used.
Using Boyle's law
P1V1 = P2V2
P1 is the initial pressure = 1.5×10^5Pa
V1 is the initial volume = 0.08m3
P2 is the final pressure (required)
V2 is the final volume = 0.04 m3
From the formula, P2 = P1V1/V2
P2 = 1.5×10^5 × 0.08 ÷ 0.04
= 300000Pa or 3×10^5 Pa.
