Answer:
10.8 days (3 sig.figs.)
Explanation:
All radioactive decay is 1st order decay defined by the expression A = A₀e^-kt
which is solved for time of decay (t) => t = ln(A/A₀) / -k
A = final weight = 1.0 gram
A₀ = initial weight = 16.0 grams
k = rate constant = 0.693/t(1/2) = 0.693/2.69 days = 0.258 days⁻¹
t = ln(1/16) / -0.258da⁻¹ = (-2.77/-0.258) days = 10.74646792 days (calculator)
≅ 10 days (1 sig. fig. based on given 1 gram mass)
Answer:
11 electrons total and 23amu
Explanation:
This tells us that sodium has 11 protons and because it is neutral it has 11 electrons. The mass number of an element tells us the number of protons AND neutrons in an atom (the two particles that have a measurable mass). Sodium has a mass number of 23amu.
and D. to identify minerals
Answer:
It's an open system, tranfering heat through a rigid, diathermal wall and matter through an imaginary and permeable wall, and it is not at steady state.
Explanation:
- An <em>open system</em> is that that interacts with its surroundings exchanging energy and matter. In an open pan with boiling water you have an open system because steam (matter) is leaving the system, as well as heat (energy) through the pan/stove.
- A<em> boundary</em> is what separates the system from its surroundings, there are many types of boundaries, based on how they transfer energy they can be diathermal (conducting heat) or adiabatic (insulating), on their rigidity they can be rigid, flexible, imaginary or movable and based on their permeability. For the system described we have an imaginary boundary on top that is also permeable allowing matter to go out or in the system, and another wall (the stove/pan itself that is rigid and impermeable avoiding the loss of matter and diathermal, allowing the conduction of heat.
- It is said that a system is at a<em> steady state</em> when the variables that define that system remain constant over time. In an open pan, you can't fully control those variables, you'll have matter and energy scaping from it with no way to regulate it.
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Answer:
Carbs,lipids,proteins,nuclei acids
Explanation:
