Activation energy is a thermodynamic barrier that must be overcome before products are formed in a reaction. It is the minimum amount of energy needed for a reaction to occur. The energy can be in the form of kinetic or potential energy. This concept was introduced by Svante Arrhenius, which brought about the Arrhenius equation which is a formula used to determine rate of reactions.
Making repeated separations of the various substances in the pitchblende, Marie and Pierre used the Curie electrometer to identify the most radioactive fractions. They thus discovered that two fractions, one containing mostly bismuth and the other containing mostly barium, were strongly radioactive.
<h3>What was surprising about pitchblende?</h3>
Since it was no longer appropriate to call them “uranic rays,” Marie proposed a new name: “radioactivity.”
Even more surprising, Marie next found that a uranium ore called pitchblende contained two powerfully radioactive new elements: polonium, which she named for her native Poland, and radium.
<h3>Why is radium more radioactive than uranium?</h3>
It is 2.7 million times more radioactive than the same molar amount of natural uranium (mostly uranium-238), due to its proportionally shorter half-life.
Learn more about highly radioactive elements here:
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Answer: Option (C) is the correct answer.
Explanation:
Molecules in a liquid have less force of attraction as compared to solids. But liquid molecules have more force of attraction as compared to gases.
Since molecules of a gas are held together by weak Vander waal forces, therefore, they expand to fill the container whereas molecules in a liquid are not expanded in a container like gases because of more force of attraction within molecules of liquids as compared to gases.
Hence, a liquid can take the shape of container in which it is kept.
Thus, we can conclude that out of the given options, a liquid change to take the shape of its container but NOT expand to fill the container itself because the particles of a liquid are held together loosely enough to flow, but not so loose that they expand.
Answer:
Lithium
Explanation:
I believe it is Lithium. It can easily be cut with a knife and is the 3rd lightest non gas on the periodic table that is not a gas.
