The main class of high-temperature superconductors are in the class of copper oxides (only some particular copper oxides) especially the Rare-earth barium copper oxides (REBCOs) such as Yttrium barium copper oxide (YBCO).
<h3>What superconducting material works with the highest temperature?</h3>
As of 2020, the material with the highest accepted superconducting temperature is an extremely pressurized carbonaceous sulfur hydride with a critical transition temperature of +15°C at 267 GPa.
<h3>How do high-temperature superconductors work?</h3>
High-temperature superconductivity, the ability of certain materials to conduct electricity with zero electrical resistance at temperatures above the boiling point of liquid nitrogen, was unexpectedly discovered in copper oxide (cuprate) materials in 1987.
Learn more about high temperature superconductors here:
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water molecules are attracted to polar molecules and surround them.
The elements atomic number, the number of protons in the necules
<u>Answer:</u> The correct answer is Option d.
<u>Explanation:</u>
To calculate the molarity of base, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is KOH
We are given:

Putting values in above equation, we get:

Hence, the correct answer is Option d.
Answer : The value of rate constant is, 
Explanation :
First we have to calculate the rate constant, we use the formula :
Expression for rate law for first order kinetics is given by:

where,
k = rate constant = ?
t = time passed by the sample = 4.84 s
a = initial concentration = 4.17 M
a - x = concentration after time 4.84 s = 3.56 M
Now put all the given values in above equation, we get


Therefore, the value of rate constant is, 