Answer:
d. The formation of a covalent bond between two amino acids
Explanation:
In a chemical reaction, a substance transforms into another with different chemical properties and a different formula. Bonds are created and/or destroyed. It must obey the law of conservation of mass and the law of conservation of elements.
<em>Which of the following is a chemical reaction?</em>
<em>a. Making a hydrogen bond between a water molecule and a sugar molecule. </em>NO. This is a physical change in which sugar dissolves in water but both their chemical identities remain the same. The hydrogen bond is a force of attraction and not a real bond in which electrons are gained, lost or shared.
<em>b. The melting of ice.</em> NO. This is a physical change. Solid water turns into liquid water but the identity of the molecules is the same.
<em>c. Changing a carbon atom to a nitrogen atom by radioactive decay.</em> NO. This is a nuclear reaction in which a new element appears but it is not a chemical reaction because it does not fulfill the law of conservation of elements.
<em>d. The formation of a covalent bond between two amino acids.</em> YES. A new bond is created and a protein dimer is formed.
Answer: 
moles
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to molecular mass , occupies 22.4 L at STP and contains avogadro's number 
of particles.
To calculate the moles, we use the equation:
Given mass of ethanol = 0.2301
Molar mass of ethanol = 46.07 g/mol
Thus there are moles of ethanol are present in the sample.
Answer:- Yes, strontum bromide and potassium sulfate gives a precipitate of strontium sulfate.
Explanations:- As per the solubility rules, all compounds of alkali metals are soluble.
Sulfate of most of the alkaline earth metals like Ca, Ba and Sr are insoluble.
A double displacement reaction takes place when strontium bromide and potassium sulfate are mixed and a precipitate of strontium sulfate is formed:
Note: (aq) stands for aqueous and (s) stands for solid and here it's precipitate.
1) use the formula PV=nRT
2) Plug in given values: P(8.77 L)= (1.45 mol)(0.0821)(293 K)
3) isolate P: P= (1.45x.0821x293)/(8.77)
4) solve: P=3.98 atm
