Grammar and missing word

source/core/sharding-introduction.txt

@@ -194,21 +194,21 @@ the balancer process migrates chunks from the shard that has the
 largest number of chunks to the shard with the least number of chunks
 until the collection balances. For example: if collection ``users``
 has 100 chunks on *shard 1* and 50 chunks on *shard 2*, the balancer
-will migrate chunks from *shard 1* to *shard 2* until the collections
+will migrate chunks from *shard 1* to *shard 2* until the collection
 achieves balance.
 
 The shards manage *chunk migrations* as a background operation. During
-migration, all requests for a chunks data address the "origin" shard.
+migration, all requests for a chunk's data address the "origin" shard.
 
 In a chunk migration, the *destination shard* receives all the
 documents in the chunk from the *origin shard*. Then, the destination
 shard captures and applies all changes made to the data during
 migration process. Finally, the destination shard updates the metadata
-regarding the location of the on *config server*.
+regarding the location of the chunk on *config server*.
 
 If there's an error during the migration, the balancer aborts the
 process leaving the chunk on the origin shard. MongoDB removes the
-chunks data from the origin shard **after** the migration completes
+chunk's data from the origin shard **after** the migration completes
 successfully.
 
 .. include:: /images/sharding-migrating.rst