Answer:
Therefore it will take 7.66 hours for 80% of the lead decay.
Explanation:
The differential equation for decay is
Integrating both sides
ln A= kt+c₁
[
]
The initial condition is A(0)= A₀,
.........(1)
Given that the 
has half life of 3.3 hours.
For half life 
putting this in equation (1)
[taking ln both sides, 
]
⇒k= - 0.21
Now A₀= 1 gram, 80%=0.8
and A= (1-0.8)A₀ = (0.2×1) gram = 0.2 gram
Now putting the value of k,A and A₀in the equation (1)
⇒ t≈7.66
Therefore it will take 7.66 hours for 80% of the lead decay.
Answer:
17.934 kg of water
Explanation:
If balanced equation is not given; this format can come in handy.
For any alkane of the type : CₙH₂ₙ₊₂ , it's combustion reaction will follow:
2CₙH₂ₙ₊₂ + (3n+1) O₂ → (2n)CO₂ + 2(n+1) H₂O
For butane:
2C₄H₁₀(g) + 13O₂(g) → 8CO₂(g) + 10H₂O(l)
2 moles of butane gives 10 moles of water.
1 mol of any substance has Avogadro number(N) of molecules in it( 6.022 x 10²³)
Mass of 1 mole of any substance is equal to it's molar mass
So, if 2 x N molecules of butane gives 10 x 18 g of water.
Then 1.2 x 10²⁶ molecules will give:
= 17.934 x 10³ g of water
= 17.934 kg of water
An osmolarity of saline solution is 308 mosmol/L.
m(NaCl) = 9 g; the mass of sodium chloride
V(solution) = 1 L; the volume of the saline solution
n(NaCl) = 9 g ÷ 58.44 g/mol
n(NaCl) = 0.155 mol; the amount of sodium chloride
number of ions = 2
Osmotic concentration (osmolarity) is a measure of how many osmoles of particles of solute it contains per liter.
The osmolarity = n(NaCl) ÷ V(solution) × 2
The osmolarity = 0.154 mol ÷ 1 L × 2
The osmolarity = 0.154 mol/L × 1000 mmol/m × 2
The osmolarity of the saline solution = 308 mosm/L.
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Yes, it is the power of material evidence that wins.
- Evidence used to support or refute a scientific theory or hypothesis is known as material evidence.
- Evidence is also used by scientists in various contexts, such as when they apply ideas to real-world issues.
- Whether a person accepts the data as proof depends on their presumptions or views regarding how observations relate to a theory.
- A creative hypothesis is developed by a scientist and may be refuted by testing it against evidence or established truths.
- Evidence can refute a hypothesis by demonstrating facts that are at odds with it. In contrast, the presence of evidence does not preclude the possibility of future, undiscovered evidence supporting the idea.
Therefore, it is the power of material evidence that wins, not the authority of experts that
proves an answer in Science.
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