Oxidation state of Pb in PbO2 is +4.
Oxidation state of Pb in PbCl2 is +2.
Oxidation state of Pb in Pb2O is +1.
Oxidation state of Pb in Pb4O3 is +6/4.
Hence option A. PbO2 is correct.
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Answer:
Magnesium carbonate doesn't dissolve in water, only acid, where it will effervesce (bubble).
Explanation:
An insoluble metal carbonate reacts with a dilute acid to form a soluble salt. Magnesium carbonate, a white solid, and dilute sulfuric acid react to produce magnesium sulfate. Colourless magnesium sulfate heptahydrate crystals are obtained from this solution.
Explanation:
<em><u>SMARTPHONE OWNERSHIP IS GROWING RAPIDLY AROUND THE WORLD, BUT NOT ALWAYS THE SAME.</u></em>
In emerging economies, the use of technology is still more common among the young and the educated
A farmer takes a selfie with a smartphone at a rally in Jaipur, India. (Vishal Bhatnagar/AFP/Getty Images)
A farmer takes a selfie with a smartphone at a rally in Jaipur, India. (Vishal Bhatnagar/AFP/Getty Images)
The chart shows that smartphone ownership in advanced economies is higher than in emerging economies.
Mobile technology has spread rapidly around the world. Today, it is estimated that more than 5 billion people have mobile devices, and more than half of these connections are smartphones. But growth in mobile technology so far has been unequal, either nationwide or within it. People in advanced economies are more likely to have mobile phones - smartphones in particular - and more likely to use the internet and social media than people in emerging economies. For example, a median of 76% across the 18 advanced economies surveyed have a smartphone, compared to a median of only 45% in emerging economies.
Smartphone ownership can vary by country, and even across developed economies. While about nine in ten or more South Koreans, Israelis and the Netherlands own a smartphone, the ownership rate is closer to six in ten in other developed countries such as Poland, Russia and Greece. In emerging economies as well, smartphone ownership rates vary significantly, from a high of 60% in South Africa and Brazil to just around four in ten in Indonesia, Kenya and Nigeria. Among the countries surveyed, ownership was lowest in India, where only 24% reported having a smartphone.
Answer:
pH = 2.77
Explanation:
Data Given:
degree of dissociation Ka = 0.057
Concentration of Methanoic acid = 0.005 M
pH = ?
Solution:
First we calculate Hydrogen ion concentration
Formula will be used
[H⁺] =
. . . . . . (1)
where
Ka = degree of dissociation
c = concentration
Put values in formula 1
[H⁺] =
. . . . . . (1)
[H⁺] = 0.0017 M
Now Calculate the pH
As we know
pH = -log [H⁺] . . . . . .(2)
Put values in equation
pH = - log [ 0.0017 M]
pH = - [-2.77]
pH = 2.77
So,
pH of methanoic acid = 2.77