Answer:
Q1. D) A single replacement reaction takes place because sodium is more reactive than hydrogen.
Explanation: 
Sodium metal reacts with water to givesodium hydroxide and hydrogen gas. A single replacement reaction takes place because sodium is more reactive than hydrogen.
Sodium easily lose electrons than hydrogen and get oxidized to 
and 
get reduced to give 
.
Q2. B) It is a single replacement reaction, and the cations in the two ionic compounds are different.
Explanation: 
where Sodium is a metal and 
is an ionic compound. Na being more reactive than Al, displaces it from its salt solution.
Q3. D) 
Explanation: A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution.Thus zinc can easily lose electrons as compared to hydrogen and result in the formation of zinc sulfate and hydrogen.
Q4. False
no reaction
Explanation: As zinc lies lower in reactivity series, it is less reactive than calcium. It will not be able to displace calcium from its salt and hence no reaction occur. Thus the given statement is false.
Q5. False
Explanation: A double displacement reaction is one in which exchange of ions take place. Thus an element replaces another element and not same element.
A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution. Thus one element should be different from another element.
Q6. A)
, because K retains the same charge throughout the reaction
Explanation: A balanced chemical reaction is one in which the number of atoms on both sides of a chemical equation are same. Also K has an oxidation state or charge of +1 in 
as well as 
The amount, in grams, of N that the sample will contain will be 2.1 grams.
<h3>Stoichiometric mass ratio</h3>
According to the problem. the mass ratio of H and N in ammonia is 4.7:1.
In other words, every 4.7 grams of H in ammonia must have 1 gram of N.
Now, in a particular ammonia sample, 10 grams of H is present.
The amount of N present can be calculated from the standard mass ratio.
4.1 grams H = 1 gram N
10 grams H = x
4.1x = 1 x 10
x = 10/4.1
x = 2.1 grams
Thus, the mass of nitrogen in the ammonia sample will be 2.1 grams.
More on mass ratios can be found here: brainly.com/question/14577772
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Answer:
Value of coefficient of kinetic friction is 0.26 .
Explanation:
Given:
Mass of wooden crate, m = 12.5 kg.
Horizontal force to keep the block moving with constant velocity, F = 32.0 N.
Since, the block is moving with constant velocity.
So, net force experience by it is zero.
Therefore, fore of friction is equal to applied force.
Now, force of friction , 
( here 
is coefficient of kinetic friction and N is normal force)
Therefore, 
Now, both forces are equal.
The value of coefficient of kinetic friction is 0.26 .
Hence, it is the required solution.
Answer:
Large-scale natural disasters
Explanation:
The emergency situation that rescue workers could be in that would make it difficult for them to get energy to their electrical devices is "Large-scale natural disasters"
Large-scale natural disasters are very destructive and devastating. Their impact and effect can range from destruction of infrastructures, properties, social amenities and even ecosystems. When such disasters break out, they destroy things and which leads to difficulty in accessing certain amenities. Rescue workers even find it difficult to access energy for their electrical devices - because there is power outage.
Some of these large-scale natural disasters are earthquakes, tornadoes, hurricanes, floods, etc.
Answer:
you need to send us the figure
Explanation:
