Answer:
10.78 → 4 significant figures, pH = 10.78 → [H⁺] = 1.66ₓ10⁻¹¹ M
6.78 → 3 significant figures, pH = 6.78 → [H⁺] = 1.66ₓ10⁻⁷ M
0.78 → 2 significant figures, pH = 0.78 → [H⁺] = 0.166 M
pH always can be expressed by at least 4 significant figures. The [H⁺], can be expressed by, at least 3 significant figures
Explanation:
Significant figures are the numbers of a measurement that have certainty plus a doubtful number (it is associated with the uncertainty in the measurement). For example, if we measure a paper with a ruler and the ruler measures up to centimeters we can say that the paper is 7.5 cm long, with which we know that the paper is 7 cm + 0.5 cm which we associate with uncertainty. In this case we talk about two significant figures. If the sheet measured 7.57 cm we would already be talking about a more precise measurement and in this case with 3 significant figures.
10.78 → 4 significant figures
6.78 → 3 significant figures
0.78 → 2 significant figures
To determine [H⁺], we apply 10^-pH
10⁻¹⁰°⁷⁸ = 1.66ₓ10⁻¹¹ M
10⁻⁶°⁷⁸ = 1.66ₓ10⁻⁷ M
10⁻⁰°⁷⁸ = 0.166 M
Answer: Region 3
Explanation: The temperature and time graph suggests that region 3 is the region in which the substance can co exist in both the phases that is solid phase and liquid phase.
Region 1 explains that the the solid has just started melting and there occurs a break point and then region 2 again explains that the solid is taking more time with temperature to get converted into the liquid and thus region 3 explains the equilibrium between the two phases.
1.A law is an observation; a theory is the explanation of that observation.
2.A theory requires experimentation under various conditions. A law has no such requirements.
3.A theory may become obsolete with time. This is not the case with a law.
4.A theory can be replaced by another better theory; however, this never happens with a law.
5.A theory may be strong or weak according to the amount of evidence available. A law is a universally observable fact.
Hope this helps:)
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How many grams of Cu would be needed to react with 2.0 mol HNO3?
<span>by the equation </span>
<span>3Cu + 8HNO3 --> 3Cu(NO3)2 + 2NO + 4H2O </span>
<span>2.0 mol HNO3 reacts with 3/8 ths as many moles of Cu = 0.75 moles of Cu </span>
