What happens when a MySQL Cluster node is disconnected I am trying to design a multi-master clustered MySQL database which will be spread through out the country.

The main reason for having a cluster is so that when the internet, in one location (or node), is disconnected, that location should still be able to read and modify the contents of the database locally. So that when the internet connection is restored, the rest of the cluster get updated.

I've went through the MySQL cluster documentation, however, I couldn't find this specific question. Is it possible to achieve this using MySQL cluster?
In short, MySQL Cluster isn't a good fit for your use case.

MySQL Cluster's shared-nothing architecture provides excellent protection against component-level failure.  When nodes fail or become unresponsive, Cluster takes quick action to disable affected nodes.  It does not focus on conflict resolution, instead works to avoid the "split-brain" problem where a single cluster begins processing work in parallel without coordination.  This is exactly the opposite the use case you describe:  Database activity continuing as normal when partitioned by the network, to be reconciled later when everything reconnects.

MySQL Cluster also typically does not fare well when nodes lack low-latency connections.  Relying on WAN connections between nodes is a bad idea.  MySQL Cluster does support asynchronous replication between data centers.

You might consider using multi-source replication in MySQL Server 5.7 as an alternative.