In Wireless Sensor Networks (WSNs) keeping the network connectivity is a challenging task because failure in some nodes may cut off the communication paths between other nodes. A k-connected network remains connected after failure in any k-1 nodes, hence we can consider the k value as a metric for measuring the connectivity robustness of WSNs. In this paper we consider the effect of random node distribution and transmission range of nodes on k value of WSNs. To evaluate the effect of node count and transmission range on k, we generated 1000 random topologies with different transmission range and node count and measured the k value of established networks. Our simulation result showed that in a field of 1000 x 1000 m(2) area, with unified random distribution we need at least 200 nodes with minimum transmission range 80 m to expect a network with k >= 1. Also, the simulation results showed that random distributing of up to 500 nodes with transmission range lower than 80 in a field with mentioned area, generally leads to disconnected networks.