What does below science rebus mean?

Ag Ag Ag
Ag SPOON Ag
Ag Ag Ag

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

Let's play a word game. Following are some meaningless words that can be completed by adding random letters on either side of the word.

For example, the word "rdo" can be formed into "pardon".

Using the same technique, can you complete the given words?
ecalc
airb
rinci
tibac
uidel
gorit
igna
eyho

What's the only room from which no one can enter or leave

As shown in the image, the nine Dogs are square fenced. By constructing just two square fences can you make sure that two Dogs cannot meet each other without crossing the fence?

A person was killed at a house party. When the police arrive, there are six people present in the house who are the friends of the victim. The name of the friends is Rohit, Aman, Nick, Gagan, and Randy.

Near the dead body, they find a few numbers written with blood by the victim on the floor. The numbers are 8, 5, 4, and 11.

The police arrests one of the friends for the murder. Whom did they arrest and why?

What has lots of eyes, but can’t see?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

What number comes next in this sequence:
7 8 5 5 3 4 4 _